Insect Pests in NY State
6.2.1 White Grubs
are some 17 insects that can cause serious injury to turfgrass in NY State and
these belong to six general complexes: (1) white grubs, (2) weevils, (3) chinch
bugs, (4) caterpillars, (5) ants and (6) leatherjackets. White grubs are scarab
beetle larvae that live in the soil where they prune grass roots or otherwise disrupt
the rooting zone. Weevil larvae begin as stem borers, then crown feeders, and
then as adults they become foliage feeders. Chinch bugs are small, fast-moving
sucking insects that live at the soil surface. Caterpillars include black
cutworms that dwell in burrows
at the soil surface, and fall armyworms that move aboveground as foliage
feeders. Ants are relevant when their nests disrupt the surface of the ground.
Leatherjackets are the soil-dwelling larvae of crane flies that injure grass
both above- and below-ground. The injury caused by these insects can be
difficult to differentiate from each other and from certain plant diseases.
Nevertheless, control decisions must be based on a correct identification of
the insect pest, which means recognizing the injury and knowing how to identify
the insect complex and insect species involved. Diagnosis is fundamental
because the timing and type of control tactics will depend on the particular
species involved, and moreover because chemical control products have labels
specific to particular groups of insects. A misdiagnosis means that applicators
will not be in full compliance.
6.2.1. Major insect pests of NY State turfgrass.
Most damaging life
Asiatic garden beetle
Black turfgrass ataenius
Green June beetle
May and June beetles
Northern masked chafer
Annual bluegrass weevil
Hairy chinch bug
European crane flies
Tipula oleracea, Tipula paludosa
Root zone, Soil surface
Lasius neoniger, others
1Grub, caterpillar, nymph and maggot are
terms for the immature life stage of different insect groups
6.2.1 White Grubs
grubs are the larval, or immature, stages of scarab beetles, constituting the
most diverse, widespread and damaging group of turf pests in the Northeast U.S.
In NY these include four native species (black turfgrass ataenius, green June beetle,
May or June beetles, northern masked chafer) and four introduced species
(Asiatic garden beetle, European chafer, Japanese beetle, Oriental beetle).
While this pest complex occurs across the entire state, the most prevalent
species at any one site will vary considerably. Up to four species might occupy
the same patch of turf, but the composition and relative abundance of those
species will depend on local conditions due to diverging habitat preferences.
For instance, Japanese beetles may be more prevalent in irrigated turf such as
golf course fairways, while European chafer might be more prevalent in
non-irrigated rough. The green June beetle is an exception to widespread
occurrence as it is not known outside of southeastern NY.
have well-developed mandibles for chewing on grass roots. The younger larvae
may ingest a high proportion of organic material in addition to feeding on
fibrous roots. All cool season grasses are susceptible, as well as some species
of forage, field and nursery crops. While the adults of some species feed and
are damaging to ornamental plants in their own right (e.g., Japanese beetle,
Asiatic garden beetle), the adults of another species may not feed at all
(e.g., European chafer). No adults feed directly on turfgrass.
are truly subterranean, moving horizontally through the soil to track food
resources and moving vertically in response to drought and cold temperatures.
Adults are generally strong fliers, mobilizing to locate mates and egg-laying
sites. Because of this, having a lot of adults does not necessarily translate
to a lot of grubs. Local control of adult populations will not solve grub
problems, nor will local control of grub populations solve adult problems
(e.g., Japanese beetle feeding on ornamentals).
of most species rely on female-produced pheromones to attract males for mating.
One exception is the European chafer. Males and females of this species
aggregate at dusk around prominent trees, vegetation or structures to find mates
as they apparently do not use long-distance pheromones. Adult females lay eggs
below ground, either singly or in small groups. After egg hatch, development
proceeds through three larval instars, then prepupa, pupa and adult.
most species complete one generation a year and overwinter as third instars. As
winter approaches, larvae descend to stay below the frost line, and ascend in
spring as the frost line recedes. They descend once more for pupation. It is
the prepupa that fashions the earthen cell in which the pupa resides until the
adult emerges and crawls to the surface. Corresponding to its small size, the
black turfgrass ataenius can complete two generations a year and overwinters as
an adult. The inverse is true for the large May or June beetle grubs, which may
require 2-3 years to complete a single generation.
damage is attributed to the large third instar due to extensive pruning
(chewing) of the roots at the soil-thatch interface. This kind of injury
disrupts water and nutrient flow and, if accompanied by drought stress, the
grass will quickly die. High populations can kill extensive areas of turf.
Unlike other species, larvae of the green June beetle cause damage by their
active tunneling through the root zone, not by direct feeding on roots. Most of
their nutrition is obtained by ingesting soil organic matter rather than living
Diagnosis. Larvae are
“C”-shaped, with six legs, and well-developed mandibles attached to a defined
head capsule. The eight species that occur in NY can be differentiated based on
two characters of the abdomen: the raster pattern and the anal slit. The raster
pattern is the specific arrangement of hairs, spines and bare patches on the
ventral surface of last abdominal segment. The anal slit can be straight or
“Y”-shaped. With practice and the help of a hand lens, these features can be
distinguished in the field at least for the larger third instars. These two
characters are definitive for identifying turf-infesting grub species in NY.
More information can be found at ohioline.osu.edu/hyg-fact/2000/2510.html.
turf is heavily damaged it will feel spongy, not firm, underfoot. It will peel
back from the soil like a carpet because the root system has been disrupted or
devoured. Above ground, there will be thinning, increased susceptibility to
drought and ultimately increased susceptibility to weed invasion. If grub
populations do not cause visible damage, then their predators might. The grubbing
activities of vertebrates like raccoons, skunks and moles can be highly
problematic. It is common that indirect grubbing damage is more troublesome
than direct grub damage.
goal is to monitor the activity of adults in anticipation of a preventive
application around the time of egg hatch, Japanese beetles can be monitored
with vane traps (baited with a pheromone and floral lure), European chafer by
observing mating swarms, and Asiatic garden beetle by nocturnal sweeping of the
grass with an insect net or by its attraction to lights or light traps. More
often, however, it is the damaging larval stage that has to be monitored in
support of decision-making. To detect larvae or assess their abundance, you
have to dig. Unlike certain other turf insects such as caterpillars, disclosing
solutions will not force white grubs to the surface. Use a golf course cup
cutter, bulb planter, or shovel to examine soil cores for grubs in the root
zone. Depending on the size of the species, eggs and first instars are relatively
difficult to find, while second and third instars are relatively easy to pick
out of the soil.
potential for future damage can be predicted by sampling for grubs that have
not yet caused significant injury. The best time to sample is early August in
southeastern NY and mid-August upstate. Egg hatch and grub development,
however, may be delayed by cool or dry weather and may also vary from species
to species. A sampling scheme should be based on identified problem areas, susceptible
areas, and areas that otherwise require better protection (e.g., front lawns,
fairways). High priority and high risk areas should be sampled more completely
to reduce the chances of overlooking a damaging infestation.
Table 6.2.2. White grub treatment
Number of grubs per
Asiatic garden beetle
Black turfgrass ataenius
Green June beetle
Northern masked chafer
May and June beetle
14.25-inch diameter soil core of the
standard golf course cup cutter
have been established as general guidelines for treatment (Table 6.2.2). If
several areas are at or above the threshold, intervention may be warranted.
Remember, turfgrass that receives sufficient water and has a healthy root
system will tolerate higher numbers of grubs than the suggested thresholds.
Extensive research in upstate NY shows that insecticide treatments are needed
only 20% of the time on home lawns and golf course fairways. In other words, if
the decision-making process is bypassed by the consistent use of an early
season preventive insecticide, the application may have been unnecessary four
times out of five.
– Cultural control. There
is no specific host plant resistance among turf grasses to white grubs. It is
therefore not possible to select a grass that eliminates grub problems.
Kentucky bluegrass and creeping bentgrass, however, have a spreading growth
habit that is beneficial for filling in bare patches caused by grubs.
Endophyte-enhanced grasses (e.g., some perennial ryegrass and tall fescue) may
be more tolerant of drought stress and recover more quickly from grub damage
even though they do not confer resistance per se. Soil moisture and fertility
affect the expression of damage by white grubs. Actively growing turf with a
good root system may tolerate populations up to 50% higher than treatment
thresholds without showing signs of injury. The recovery of grub-damaged turf can
be hastened with autumn fertilization. A high-nitrogen application in the
spring, however, is detrimental because it weakens the grass by encouraging
shoot development without a good root system. Counteract root loss with regular
watering and counteract thinning of the stand with overseeding.
– Chemical control.
There are two basic insecticidal approaches to managing white grubs. One is to
make a preventive summer application of a slow-acting and long-lasting
material, like chlorantraniliprole or imidacloprid, that will prevent
subsequent infestations. The second is to wait until mid-August, after egg
hatch, and sample for the presence, abundance and distribution of grubs. Areas
with populations above threshold levels can be spot treated with a curative
insecticide. Data support that imidacloprid can still be effective if used in
August. Trichlorfon is a fast-acting, short-lived insecticide that is usually
effective in both September and October. However, practitioners should consider
the relatively high EIQ of trichlorfon when selecting a treatment strategy.
Entomopathogenic nematodes are another curative treatment that can be
considered, and are discussed later in this chapter.
of a preventive insecticide may be warranted in areas that consistently suffer
damaging grub populations, or in risk-adverse situations with high value or
high priority turf. The advantages of this approach are (1) the available
chemistries have a relatively low EIQ, mammalian toxicity and low rate of
active ingredient, (2) a fairly forgiving window of application, (3) if the
application fails, other alternatives are available as a late season backup,
and (4) no scouting is required. One drawback of this approach is that
applications are made too early in the season to scout for grubs. Contrary to
best IPM practices, this means that population levels cannot be assessed and
compared to damage thresholds for decision-making. A second drawback is that
insecticides with longer residuals will also have longer windows of exposure to
non-target fauna, which have a role in the natural regulation of pest
populations and other beneficial processes.
contrast, use of a curative insecticide can be based on known populations. The
specific advantages are that (1) scouting can be used to assess population
levels, locations, and species present, (2) intervention decisions can be made
based on thresholds, (3) spot treatments can be made over smaller areas, and
(4) the fast-acting insecticide, trichlorfon, degrades rapidly. Aside from the
labor and cost of scouting, a main drawback of this approach is that there is
usually no second chance if the application fails. A second drawback is that
trichlorfon has relatively high EIQ, mammalian toxicity and rate of active
spring treatments for grub control are not recommended. Although grubs are
feeding vigorously at that time of year between overwintering and pupation, the
feeding time is relatively short, the grubs are as large as they are going to
get and are very tolerant of insecticides. In addition, most damage has already
occurred and the spring flush in grass growth can usually compensate for grub
damage. Regardless of approach, the goal of treatment is never to eradicate
completely, but to reduce the population below damage thresholds.
broad-spectrum, long-residual insecticide. This compound is widely relied upon
for white grub control in commercial turfgrass. It mostly functions as a
systemic so it should be well watered in to reach the roots where it will be
taken up by the plant after an activation period. The optimal time to use
imidacloprid is at the time of egg laying and egg hatch. Nevertheless, its
long-residual gives it a relatively forgiving window of application, from early
June to mid-August. While largely used preventively, before scouting is
possible, recent research shows that it may be effective against Japanese
beetle as late as second instar. Because this developmental stage can be
scouted, it opens opportunities to use imidacloprid as a curative. This
approach might be suitable if scouting reveals a previously undetected and
widespread infestation that is predominately second instar Japanese beetle. In
this case, imidacloprid would be a viable option to pursue before a widespread
application of a curative alternative. But unless a manager has a good
understanding of the timing and potential asynchrony of population development
(e.g., Japanese beetle can lay eggs over a period of more than two months),
caution should prevail.
commercial applications of imidacloprid products are restricted-use statewide
in NY. In addition, the sale, use, and distribution of consumer products are
not allowed in Nassau, Suffolk, Kings or Queens Counties.
Chlorantraniliprole is a broad-spectrum
and long-residual insecticide. It can be applied as soon as early April for
preventive control, and in August and possibly early September for early
curative control. Later season applications may require the high label rate for
effective control of second instar larvae. All species of white grubs are
susceptible to this insecticide. There is also proven efficacy against many of
the other turf-infesting insects in NY. Given its long-residual activity,
season long control is probable against white grubs and possible against other
insect pests. Subsequent infestations of caterpillars, billbugs, annual
bluegrass weevils and European crane flies might be suppressed in
chlorantraniliprole-treated turf. When feasible, use scouting to determine
whether insecticide applications against those other pest species might be
Trichlorfon is a fast-acting,
short-residual insecticide recommended for curative spot treatments.
Trichlorfon is highly soluble and penetrates the thatch layer better than most
products. It has an extremely short period of residual activity (7-10 days) and
a reduced half-life in alkaline soils. This product is recommended as a
late-season curative and should be applied after the grubs have been located,
up to as late as mid-September. It should be noted that trichlorfon has a
relatively high EIQ, and that carbaryl is the only alternative to trichlorfon
for late season and fast-acting control.
- Biological control. Three biological control agents are commercially
available for management of white grubs in turf: entomopathogenic nematodes,
entomopathogenic fungi, and the bacteria that cause milky spore disease.
Nevertheless, all alternatives have relatively poor or inconsistent results in
the field. Therefore, while turfgrass managers might experiment with these
products, they should not rely on them for grub management in high-priority
areas. They may also be better than nothing in areas where cultural management
is insufficient and chemical treatments are either not desired or not allowed.
Entomopathogenic nematodes can be effective parasites of white grubs. Although
they are sometimes as effective as chemical insecticides in laboratory trials,
field results are inconsistent and failures are common. Reasons for poor field
results include insufficient water at time of application, improper selection
of nematode species, improper storage and handling of the nematodes, and
unsuitable environmental conditions.
work in concert with a mutualistic bacterium that they carry in their guts. The
infective juvenile stage of nematodes lives freely in the soil; when the
juveniles encounter a suitable insect host, they enter through natural openings
(e.g., mouth, spiracle or anus) or are sometimes able to penetrate the insect's
cuticle. Inside the host, the nematodes travel to the gut and deliver the
lethal bacteria that they vectored inside. The bacteria multiply rapidly,
releasing a toxin that kills the host in 1-2 days. The nematodes also multiply
inside the host until resources are depleted. At that point, a new generation
of infective juveniles exits the cadaver to search for another host in the
the available commercial isolates of nematodes, Heterorhabditis
bacteriophora is the species recommended for the management of white grubs.
S. glaseri are also effective but may not be available commercially.
They should be applied while grubs are still young and most susceptible and
before they have caused significant damage. Follow sampling suggestions above,
and apply nematodes in areas where high populations have been confirmed. Many
types of pesticide sprayers can be used. Use low pressure (< 300 psi), and
remove any screens finer than 50 mesh. A hose-end sprayer or watering can is
ideal for small-scale applications. Apply a minimum rate of 1 billion nematodes
per acre, regardless of the manufacturer’s directions.
nematodes are harmed by ultraviolet light, they should be applied at dusk or on
a cloudy, rainy day. The nematodes use the thin film of water surrounding soil
particles for movement. Irrigation (1/4 inch) after a nematode application is
thereby suggested to optimize soil conditions and to help move nematodes
through the thatch. A light irrigation before the application will also reduce
the chances of nematodes sticking to grass blades on the surface. Users are
advised to check viability by examining nematodes for movement with a hand lens
before application and again in a sample collected from the sprayer output.
Beauveria bassiana (the “white muscardine” fungus) is a common
soil-borne fungus that has been selected for its virulence to certain insect
pests. When conidia attach to the insect cuticle, they germinate, penetrate
with the growing hyphae, and proliferate within the insect’s body. Moist
conditions favor germination, followed by infection of the insect host 1-2 days
later, and ultimately death. The white appearance of the cadaver’s surface is
due to the conidia produced by the mature reproductive structures of the fungus
as they reemerge from the host. These infected cadavers serve as inocula for
secondary spread of the pathogen in the environment.
commercial product of Beauveria bassiana is produced through
fermentation. Conidia (spores) are harvested and formulated into a sprayable
liquid. Younger white grubs should be targeted because they are more
susceptible than third instars. After application, the area should be kept wet
to promote germination and subsequent infection. Speed and efficacy of the
product will depend on the number of spores contacting the insect, the age and
susceptibility of the grub and the environmental conditions.
Milky spore disease powder is produced by grinding up living, diseased Japanese
beetle grubs infected with Paenibacillus popilliae. Commercial preparations
of milky spore powder are widely used for the biological control of Japanese
beetle. Nevertheless, the efficacy of current formulations has not been
scientifically substantiated in the field, leading to questions about the
usefulness of this biological control agent for white grub management. Users
must also be aware that the bacteria in formulated products have been selected
for infectivity to Japanese beetle grubs and are of no value against other
common grub species infesting turfgrass in NY. This host specificity is
highlighted on the product label. While Asiatic garden beetle, European chafer
and Oriental beetle harbor the bacteria in natural populations, the commercial
variety is specific to Japanese beetle.
scouting, you may find milky grubs that are naturally infected with local
strains of bacteria. The widespread occurrence of this pathogen under natural
conditions means it does have prospects for biological control of white grubs.
But, this will depend on further research and development to transfer
laboratory virulence into field efficacy, as well as selecting more virulent
bacteria that act against more species of scarabs under broad climate
conditions. Practitioners seeking alternatives to chemical insecticides can try
this product, but should not rely upon it.
bluegrass billbug (BGB, Sphenophorus parvulus) and the annual bluegrass
weevil (ABW, Listronotus maculicollis) are native weevil species. BGB is
most injurious in high-cut, lower maintenance turf such as home lawns, athletic
fields and golf course roughs. It impacts turf throughout the northern U.S. ABW
is most injurious in low-cut, high maintenance turf such as golf course greens,
tees and fairways. Until approximately 20 years ago, outbreaks were largely
limited to southeastern NY, but now the area of impact has expanded throughout
much of the state, north to New England and Quebec, west to Ohio, and south to
BGB and ABW, females chew holes into the grass stem and insert eggs. Young
larvae live as stem borers, chewing and consuming tissue within the relative
protection of the stem and filling it up with frass (insect excrement) that
looks like sawdust. When they outgrow the stem, older larvae will drop down to
the soil surface where they forage out to chew on surface roots and crowns.
Adults feed on grass blades but cause little damage. Both species develop
through five larval instars, prepupa, pupa and adult. Pupation takes place in
the top layer of the soil. BGB completes only one generation a year, while ABW
completes two to three, and as many as four in southeastern NY.
of both species are capable walkers, and largely disperse on foot even though
they are capable of flight. In autumn, they mobilize to overwintering sites
away from developmental areas. BGB adults, for instance, may settle into where
sidewalks meet the lawn. ABW will seek out the relative protection of tree
litter and tall grass, and may be most prevalent along defined tree lines or
hedgerows bordering fairways.
have long snouts that are the hallmark of the weevils. BGB adults measure ~1/4
inch long, or about twice the size of ABW (~3/16 inch long). In addition to
overall size, BGB adults can be differentiated from ABW because their antennae
arise from the base of the snout, rather than the tip. Newly emerged adults,
known as “callows” or “tenerals,” are chestnut to brown in color, making the
young adults distinguishable from mature adults that are dark grey to black.
bodies of BGB and ABW larvae are straight to slightly curved and creamy white
in color with a well-defined brown head capsule. Unlike most beetles, weevil
larvae are legless, meaning that they are easily distinguished from white
grubs, which have six legs and a “C”-shape.
caused by the stem boring and tunneling activities of younger larvae can be
revealed through the “tug-test.” Brittle or weakened stems are easily pulled up
by hand. Unlike white-grub injury, the soil and root zone remain firm and not
spongy. BGB-damaged turf appears wilted, as if drought stressed, but it will
not respond to watering. Damage is ultimately expressed as growing brown
patches, especially near drought-prone edges such as pavement where grass may
be more susceptible to heat or water stress. To distinguish BGB from drought
stress, look for the frass as small pockets of sawdust-like material in the
thatch or inside grass stems. BGB is most prevalent and damaging in Kentucky
bluegrass. Damage is most apparent from late June through August.
injury is usually expressed as growing areas of yellow and brown spots first
noticed around the collar and perimeter of greens, tees and fairways. Early ABW
damage has anthracnose-like symptoms and is frequently confused with this
pathogen. Damage will be most prevalent in annual bluegrass, the favored host.
It is unknown whether ABW can actually complete its life cycle on other hosts,
even though it is capable of feeding on creeping bentgrass and perennial
ryegrass. High populations of ABW will cause substantial areas of dead turf in
highly visible and prominent areas of golf course playing surfaces.
– Decision-making. BGB
adults are most active in spring, from mid-May to June. It is common to see
them strolling across pavement or sidewalks in the mid to late afternoon. One
way to monitor them at this time of year is with pitfall traps. Make a hole
with a standard golf course cup cutter, insert a plastic cup that fills the hole
and is submerged to the rim, and add an inch of water with some dish detergent.
If 7-10 billbugs fall in over a 2-3 week period, injury can be expected in the
surrounding turf. Another approach in spring is to observe adults walking on
paved surfaces adjacent to turf. Injury can be expected if >2 are observed
per minute. For the larvae, tolerance thresholds are 8-12 per sq. ft.
– Intervention. If
potentially damaging populations are detected, chemical control applications
should be made between mid-May and late June. This window targets adults once
they have emerged from overwintering sites and before they lay eggs. It is best
to mow before the application and irrigate lightly afterwards. This
intervention should prevent severe damage by larvae in July and August.
areas with persistent problems, host plant selection should be considered. One
of the most susceptible cool season grasses is Kentucky bluegrass. This species
should be avoided in favor of more tolerant alternatives. Endophytic cultivars
of tall fescue and perennial ryegrass are also good options because they reduce
– Decision-making. ABW
can be challenging to monitor due to its small size. In the spring, mower
baskets can be monitored for adults because they are picked up along with
clippings. This can be a useful way to stay abreast of when adults are
appearing in spring, and, with more careful monitoring, on which areas of the
course they are most prevalent. Some areas of the course may always harbor ABW
so it is a good idea to monitor consistently those historically affected areas
from year to year. Adult ABW reinvade short-mown turf soon after snow melt and
soil thaw, from late March to April.
site-specific approach to monitor adults is to pour a soapy disclosing solution
on the turf. The standard method is to mix 1 fluid ounce lemon-scented dish
detergent in 2 gallons water and apply it over to 2-3 square feet of turf. The
soap acts as an irritant, forcing adults to emerge from the thatch and ascend
to the surface where they can be counted. Shallow soil core sampling or simply
digging around at the soil surface/thatch interface will reveal older larvae
and pupae. Older larvae look like grains of rice with brown heads; pupae
resemble adults but are creamy white until their color darkens before adult
emergence. If more detailed information is desired, larvae of all sizes (even
stem boring stages) will float to the surface when an infested core is
submerged and agitated in a saturated salt solution. This is a good way to
confirm that your adult controls were adequate; if too many larvae are found,
the application may have been poorly timed to suppress adults and another
application against adults of the developing population may be necessary.
thresholds are 30-80 larvae/sq. ft. for the spring generation. Given summer
heat stress, thresholds drop to 10-40 larvae/sq. ft. for the summer generation.
Nevertheless, field experience indicates that action may have to be taken at
thresholds as low as 5-10 larvae/sq. ft. in order to avoid injury and minimize
the threat of the subsequent generation.
Best control is achieved by targeting early spring adult populations that
represent overwintered insects returning to the short mowed turf. A preventive
insecticide application is then made to suppress adult populations before eggs
are laid. The timing of spring applications can be based on a plant
phenological indicator. The most widely used is the period that occurs between
Forsythia full bloom and flowering dogwood full bract. It is better to make the
spring application a little late than a little early, so aim for the time when
Forsythia is in full bloom and has already acquired many new leaves (i.e.,
“half gold/half green”).
a relatively insoluble insecticide that stays in the thatch where adults are
active. Chlorpyrifos and pyrethroids are the best options. Water in the
application lightly, enough to move the material off the leaves. Widespread
fairway applications are usually not necessary. It should be sufficient to
limit applications to periphery sprays along historically susceptible greens,
collars, tees and fairway perimeters. If this control fails, second generation
adults can be targeted again sometime around July 4.
southeastern NY, insect resistance to pyrethroid insecticides is well
documented. It is unclear how widespread this resistance may be across the rest
of the state. If you have made multiple seasonal applications of pyrethroid
insecticides to target adults over several years, then your local populations
may no longer be suppressed by these insecticides. Non-pyrethroid alternatives
include chlorantraniliprole, indoxacarb, spinosad and trichlorfon, which
largely target larvae. Unlike the other larvicides, chlorantraniliprole should
be applied early when overwintered adults reappear so it is fully activated
once the larvae emerge. Given the difficulties in timing applications against
ABW, all intervention approaches should be backed up by a sampling plan that
will verify product efficacy. No insecticidal products have activity against
respect to cultural control, minimizing stress (e.g., due to water deficit or
traffic) on annual bluegrass might mitigate the effects of ABW. Other than
that, reducing the amount of annual bluegrass is the only other option as this
may leave turf less favorable for the development of outbreak populations.
Overwintering adults are sometimes very abundant in white pine litter, leading
some golf courses to remove pine litter or even remove stands of white pine
trees. Tree removal is not recommended, however, because these sites are not
actually preferred locations for overwintering. Weevils will overwinter
elsewhere. We may ultimately be able to define control practices based on
managing adults in their overwintering habitats or by intercepting them as they
return to developmental sites, but these opportunities have not yet been
groups of caterpillars damage turf in NY: cutworms, sod webworms and armyworms.
Cutworms and armyworms largely refer to diverging habits of these moth larvae.
Cutworms are solitary and tend to chew through and sever the grass stem at
ground level, and then move on to the next plant. In contrast, armyworms are
gregarious feeders, and tend to move across the turf eating all edible material
in their paths. While there are a few species that can be injurious in
turfgrass of NY, the main species of concern are the black cutworm (BCW, Agrotis
ipsilon) and the fall armyworm (FAW, Spodoptera frugiperda). FAW and
BCW do not usually overwinter in NY because they are too cold intolerant.
Migratory adults reinvade the state every spring from populations that
overwinter in the southern U.S. Sod webworms on the other hand are a complex of
species that do overwinter in NY.
should also be noted that the “true” or “common” armyworm (Mythimna
unipuncta) is a sporadic invader in New York. Outbreaks typically occur in
some area of the state every 3-8 years, and result from moths blown in on
weather fronts from the southern or midwestern US. The infestation of 2012 was
the most severe and widespread on record in NY. Like FAW, true armyworms are
not known to overwinter here.
webworms are only sporadic pests and the cases are actually few where the
larvae become problematic, despite the large numbers of adults that may be
seen. Adults have snout-like projections on their face (thereby their common
name “snout moths”) and have their wings folded close to the body when at rest.
They are buff-colored and 0.5-0.75 inches long. They hide during the day. When
disturbed by mowing, however, or at dusk, they fly in a zigzag pattern and are
easy to spot.
construct silk-lined burrows through the thatch layer and into soil,
incorporating debris such as soil, sand and grass clippings in the tunnel
walls. They emerge at night to forage outside the burrows. Larvae grow up to 1
inch long, are brown to green in coloration with a series of darker spots.
Foraging birds may indicate infestations. Habitat preferences are for sunny
areas, and they can affect low to high maintenance turf (e.g., home lawns and
golf course turf). Sob webworms overwinter as larvae.
starts as small patches of yellowing or browning grass, or grass clipped off at
ground level where grass is turning brown. Look for small piles of green frass.
On low-mown turf, sod webworm damage can resemble disease, and will cause small
depressed marks of brown grass that grow in size.
highly visible adults often concern home owners, but their presence does not
indicate a pest problem. Therefore, the lawn has to be monitored for the
larvae. More often than not, damage attributed to sod webworm on residential
lawns is actually just drought stress—another reason it is important to scout
for larvae. Conduct scouting for larvae two weeks after adult flights, when
caterpillars from the new generation will be present. Scout near brown patches
by spreading the grass and looking into the thatch to find the frass. Another
way is to flush them to the surface using a soapy disclosing solution (see
number of larvae or amount of damage warrants control, use less soluble
insecticides that will stay in the thatch, such as pyrethroids. Because larvae
are most active at night, a product should be applied as late in the day as
possible. It should be watered in lightly, just enough to wash it off the
leaves and into the thatch. Spinosad and Bt are biopesticide alternatives to
conventional chemical insecticides for sod webworm management.
cutworm – Natural history. While BCW is common in low maintenance turf, it is
particularly damaging in golf course greens and tees. Each spring adult moths
reinvade NY from the southern U.S. along with spring storm fronts. This species
is apparently incapable of overwintering in areas where the soil freezes. BCW
can complete 2-3 generations a year in NY. Adults feed on flowers at night and
then locate sites in the turf where they attach eggs to the tips of grass
blades. Small larvae move across and feed on the surface. Older larvae,
however, fashion a protective burrow in the turf from which they foray to feed.
These burrows lead into the soil and are about the size of a pencil hole.
cutworm – Diagnosis and decision-making. BCW adults are dark grey and mottled with
black and brown. Larvae bear a pale stripe down the back, a greasy or oily
appearance, and have a surface integument that is rough or pebbly. Mature
larvae will get to be 1-2 inches long. Nocturnal feeding will scalp grass
around the burrow’s entrance, leaving irregular depressions that resemble
ball-marks or even dollar-spot. Low-mown bentgrass is particularly susceptible
to damage. Like sod webworms, foraging birds may help to indicate the presence
first appearance of adults in NY can be monitored in spring using either black
light or pheromone traps set out early in the season. Both traps have
limitations. Pheromone traps are relatively inexpensive and simple to maintain,
but catch only male moths. While black light traps capture both male and female
moths (along with a wide range of other insects), they are expensive and labor
intensive. Because storm-driven moths are deposited randomly, there is no
guarantee that lack of captures means that no females are present, nor is there
any way to equate capture numbers to infestation levels; thus the usefulness of
these traps is limited. A positive capture means only that chances are good
that females are present and that larvae may appear within a week.
Monitoring for larvae
should begin one to two weeks after the initial moth trap catches. Use a soap
drench (see section 6.2.2) over 3-4 areas of the green’s surface to detect
their presence. On golf course putting greens, damage may not be noticed until
the larvae are quite large or have reached the fourth instar. At this point,
the disclosing solution can confirm the diagnosis of cutworm damage. Pest
management strategies, however, should target detection and treatment of
cutworms before this stage. Thresholds will vary widely from greens and tees to
fairways. While the visible damage of only 3-4 large larvae on greens might
require a control, turf maintained at a higher cutting height can tolerate much
higher populations before thinning is apparent.
cutworm – Intervention. Cultural control takes advantage of the fact that BCW
lays the majority of eggs on the terminal portion of leaf blades, regardless of
mowing height. Most eggs can therefore be removed if the clippings are
collected. These should be discarded at least 100 feet away from susceptible
turf areas to prevent return migration of the newly hatched caterpillars.
Larvae shun feeding on Kentucky bluegrass. A 30-foot buffer of this grass
around a golf course putting green significantly reduces the incidence of
cutworms since they are less likely to cross this barrier to settle on the
greens. Another alternative is to mow greens early in the morning, between 2
and 4 a.m., when cutworms are actively feeding on the surface. Target these
mowings for three consecutive nights during the development of early instars
for each cutworm generation. Planting endophytically-enhanced varieties of
perennial ryegrass and tall fescue in appropriate areas is also an effective
way to avoid or reduce damage.
is a biologically-derived, low EIQ product that is effective against cutworms.
It works best against young caterpillars, and is relatively fast acting.
Otherwise, a range of chemistries work well for the curative control of BCW.
Early-season detection and treatment is desirable because younger (smaller)
cutworms are more susceptible than older (larger) cutworms. Higher rates might
be required for the control of large larvae and for control in high-mown turf.
Regardless, after application, irrigation and mowing should be withheld for
12-24 hours so larvae can contact the treated foliage.
spinosad, Bt-based biopesticides are an alternative to conventional chemical
insecticides. Bt is a non-living form of the bacterium Bacillus
thuringiensis that is sold and labeled for management of caterpillars,
including black cutworm, sod webworm and armyworm. This microbial toxin will
also be most effective when targeting the more susceptible smaller larvae. As
with chemical treatments, mowing and irrigation should be withheld 12-24 hours.
area of biological control, entomopathogenic nematodes have a good chance of
success in managing BCW. Use the nematode species Steinernema carpocapsae.
As with the biopesticides, apply when caterpillars are small, and follow the
recommendations described in the section under white grubs. Finally, keep in
mind that a diverse array of naturally occurring enemies, such as parasitic
wasps and flies, ground beetles and rove beetles help to suppress cutworm
hairy chinch bug (HCB, Blissus leucopterus hirtus) occurs throughout NY,
west to Minnesota, south to Virginia and north to Ontario and southeast Canada.
Home lawns are the most susceptible turf habitats. The insect is most prevalent
in areas with thick thatch, well-drained sandy soils and full sunlight. In
addition, HCB is recently and increasingly recognized as an occasional pest on
golf courses where it has traditionally been of little concern to
has piercing-sucking mouthparts that permit the nymphs and adults to extract
sap from the crowns and stems. This causes injury that produces drought-like
symptoms. Most of the cool season grasses are susceptible to feeding. Both life
stages are active and agile in the thatch and on the soil surface. HCB tends to
form aggregations and this leads to patches of localized damage.
adults are capable of flight, they largely disperse by walking. Adults will
move to overwinter in protected sites with thatch or tall grass, in debris and
around structures. When they re-emerge in the spring, egg laying is preceded by
a nearly 2-week preoviposition period. Up to 170 eggs per female are laid in
leaf sheaths and on the ground near the base of host plants. Nymphs require 4-6
weeks to develop through five instars. One generation per year is most common
in upstate NY and two generations is probably most common downstate.
Diagnosis. HCB are small and
relatively fast-moving insects. Adults are 3/16 inches long, with shiny white
wings. Nymph coloration varies from red to orange to brown. When captured by
hand, odoriferous defensive glands on the abdomen will emit a powerful and
pungent fruity smell.
habitats most susceptible to HCB damage are home lawns with full sun and sandy
soil where grass is more susceptible to drought stress. Abundance of the insect
and severity of its injury are also favored by thick thatch. July and August
are the months when the insect is most active and when most damage is
expressed. HCB feeding causes symptoms that resemble water stress and can be
misdiagnosed as such. Unlike drought, however, lawns that are heavily damaged
by HCB will not recover once wet conditions are restored. Affected grass will
turn yellow and then reddish-brown. Injury may be more prominent on the edges
of paved areas.
the soil surface should reveal the nymphs and adults. The tiniest nymphs are
bright orange/red, and the adults are quick, which makes them relatively easy
to spot despite their small size. HCB can also be detected and monitored with a
flotation cylinder. Choose a spot on the fringe of a patch of damaged grass.
Pound an open-ended coffee can ~2 inches into the soil, fill it with water, and
look for the adults as they float to the surface. Add more water as required if
it filters into the soil. A 5-10-minute observation should be sufficient.
Alternatively, remove a soil/turf core with a cup cutter or shovel, and
submerge the sample in a bucket or pan filled with water.
an infestation of HCB is detected, make several observations with the flotation
cylinder at the margin of the affected areas. More than 20 HCB per cylinder
means that action should be taken to avoid loss of turf. Population estimates
can also be made with direct visual counts. More than 10 individuals found in a
60-second search of 1 sq. ft. has been used as an action threshold, as has
20-30 per sq. ft. in a detailed search. Make these abundance estimates at
several sites around the affected area, and over time to judge whether levels
are increasing or decreasing.
have shown a great deal of variation in HCB susceptibility across different
cool season grass species and varieties. Therefore, host plant selection is a
form of cultural control that can be used. Heavily or consistently damaged
lawns should be renovated with a more tolerant grass variety. Endophytic
cultivars of tall fescues and perennial ryegrasses are the best options as they
are resistant to HCB. Reducing thatch buildup should also lessen the severity
is a naturally occurring entomopathogenic fungus that can suppress HCB
populations. Irrigation in spring and early summer helps to favor this fungus
and promote its activity in the natural regulation of HCB. There is also a
commercial formulation of B. bassiana that may be useful as an
alternative to conventional chemical insecticides.
window for insecticidal control is mid-summer when HCB is most active. The
optimal time is after overwintered adults have stopped laying eggs and before
the nymphs from their earliest eggs have matured to adults. An alternative
might be to target overwintered adults in early spring before they lay eggs.
Before any chemical treatment, turf should be watered with 15-20 gallons water
per 1000 sq. ft. Granular materials should be watered in after application.
and Natural history. Mound-building
ants are nuisance pests of golf courses in the Northeast U.S. The most
troublesome and widespread species is probably Lasius neoniger. This
small, brown ant typically builds mounds that are concentrated around the edges
of sand-based greens. A single nest may have several entrances, each with a
squat volcano-shaped pile of soil. The main nest is usually located in the
surrounding native soil. Mounds pushing up from within sand-based greens are
typically the supplemental garrisons made by foraging workers. Mounding
activity begins in early spring, increases through early summer, and declines
by late summer at which point winged reproductive adults emerge and mate.
Fertilized females then locate sites to overwinter and establish new colonies
the following spring.
for mound-building ants should begin with mid-summer mapping of problem areas
across the golf course or other turf habitat. Then, early in the following
growing season, monitor for ant activity in the areas that had high mound
pressure the previous season. This is where control measures will need to be
focused. Beyond greens, if mapping shows that the ants are moving in from golf
course roughs, treatments can be targeted at the rough/fairway interface.
Intervention. Insecticides should
only be expected to suppress, not eliminate, ant populations. Killing the
colony’s queen is difficult, and even if she dies, she can be replaced and the
colony will persist. Ant colonies are most susceptible in the early season,
when they are small and the queen is relatively weak from overwintering. When
applied early, surface insecticides such as chlorpyrifos, can give 4-6 weeks
suppression. Those applied later in season, however, may only offer 2-3 weeks
controls should focus on the perimeter of greens, collars, and roughs adjacent
to main nests. This will best target the colony at the entrances to the main
nest. An application made to the surface of the green itself will target the
entrances of the auxiliary tunnels, but miss the main nest entrance that may be
less visible in the higher-mown turf of the collar or rough.
is mixed advice about using baits as part of a control program. The baits are
granular products that contain insecticides and are broadcast applied on and
around ant mounds in turf. They may be most effective when used after an
initial knock-down application of a pyrethroid. However, the granule size of
many baits may be too large and because these ants are generalists, the baits
may not always attract them.
6.2.6 Exotic Crane Flies
European crane fly pests of turfgrass were detected for the first time in NY in
2004. Since then they have emerged as tremendously injurious insects. The
larvae are the damaging life stage, commonly referred to as “leatherjackets”
(although this may actually refer to the exuvium left behind when the adult
emerges from the pupa). Two species, Tipula paludosa (the “European
crane fly”) and Tipula oleracea (the “common crane fly”), were
originally detected in western NY. Both species are native to Europe but are
now established in three geographic areas of North America: the Pacific
Northwest (British Columbia, California, Oregon, Washington), eastern Canada
(Newfoundland, Nova Scotia, Quebec), and the eastern Great Lakes
(Massachusetts, Michigan, Ontario, New York). In NY, 2004 populations were only
detected in Erie and Niagara counties. By 2010, T. paludosa had been
detected in 11 counties (Chautauqua, Erie, Genesee, Monroe, Niagara, Oneida,
Ontario, Orleans, Tompkins, Wayne, Wyoming), while T. oleracea had
become more widespread, being detected in 18 counties (Broome, Cortland, Erie,
Genesee, Livingston, Monroe, Nassau, Niagara, Oneida, Onondaga, Ontario,
Orleans, Oswego, Seneca, Suffolk, Tompkins, Wayne, Wyoming). Based on these
observations, there are probably two separate areas of establishment, the
western Erie Canal corridor (both species) and Long Island (T. oleracea).
Until we build awareness and establish safeguards to curtail range expansion,
movement of infested materials could spread locally and regionally, across NY and
into New England and the Mid-Atlantic.
majority of the crane fly lifecycle is spent in the damaging larval stage. The
short-lived adults resemble oversized mosquitoes, but they do not feed and are
non-damaging. Adults are 2.5-3.0 cm long, pupae 3.0-3.5 cm, mature larvae 3-4
cm and eggs 0.1 cm.
completes one generation a year, with the emergence of adults occurring over a
period of 2-3 weeks at any one site in September and October. Adult females
will emerge, mate and lay most of their eggs all within the first day of their
brief reproductive lives, even though adults may persist for several days. Each
female will deposit up to 200-300 black eggs at or near the soil surface; these
eggs will hatch into larvae in about 10 days.
Larvae of T.
paludosa develop through four instars before they pupate. Active larvae
mostly inhabit the top 3 cm of the soil where they feed on root hairs, roots
and crowns of grass host plants. Larger larvae will also emerge to forage on
stems and grass blades on the soil surface. Larvae usually achieve third instar
by the onset of winter. Most damage is attributed to the feeding of rapidly
growing fourth instars in spring. By early to mid-June, larvae have achieved
their maximum size and move 3-5 cm deep in the soil. They remain in a
relatively non-feeding and inactive state until pupation, which ends when pupae
wriggle to the surface so the adult fly can emerge. The empty pupal cases
(exuviae, or the “jackets” of the leatherjackets) look like small grey-black
twigs protruding from the turf where they can be spotted on low-mown grass such
as golf course playing surfaces.
the biology of T. oleracea is quite similar to T. paludosa,
certain differences mean that management has to be tailored to the specific
species. A major difference is that T. oleracea completes two
generations a year, emerging in two peaks, one in spring (early May in western
NY) and the other in autumn coinciding with T. paludosa. The larvae of T.
oleracea never enter an inactive summer stage like T. paludosa.
Larvae overwinter as fourth instars and pupation occurs in early spring. Adult T.
oleracea differ from T. paludosa in being more capable fliers, with
females laying eggs over the course of a few days.
both species are sensitive to moisture and require wet conditions to hatch and
survive. Larvae also do best under moist conditions, but once they are third
and fourth instars they are quite tolerant of drought. Overall, mild winters
and cool summers will probably favor crane fly populations. Other turf
conditions such as thatch buildup, poor drainage and regular irrigation will
likely favor crane fly survival and population buildup.
are hundreds of native crane fly species in NY and a few of them inhabit grassy
habitats to be found emerging from turf. Native species are ostensibly
non-damaging because none have been implicated in any turf injury in NY.
Because of this, it is important to differentiate the injurious exotic species
from the natives. The best physical character to separate them is based on wing
pattern. Both exotic Tipula species have a narrow smoky band on the
leading edge of the wing adjacent to a bordering whitish band. Unlike many
native species, they have no other pigmentation on the wing. One widespread and
locally abundant native species, however, is only differentiated because there
is a break in the smoky band. Beyond that, characteristics of the male
genitalia, ventral distance between the eyes, number of antennal segments, and
length of the wing with respect to length of the abdomen permit the
differentiation of exotic crane flies from native species, and also T.
paludosa from T. oleracea. Nevertheless, species identification
should be made or confirmed by a specialist.
are serious pests of both low- and high- maintenance turf, from home lawns and
golf courses to sod farms. Based on experience in the Pacific NW, pastures and
grass seed fields can also be impacted. Spring densities of up to 70, 120 and
50 larvae/sq. ft. in highly damaged lawns, fairways and putting greens,
respectively, have been recorded in the greater Buffalo and Rochester areas.
Five categories of damage have been observed: nuisance populations of adult
flies and larvae in suburban settings, thinning damage to home lawns, chewing
damage to the surface of golf course putting greens, thinning and die-back on
golf course fairways and rough, and vertebrate predation due to skunks and
birds. In addition, it has been recently confirmed that larvae can survive
harvest, transport and installation of sod. The movement of infested sod or
other soil media will lead to new establishments and human-mediated range
the relatively synchronous emergence of local adult populations, homeowners in
suburban settings have experienced nuisance swarms of adults. Adults will
settle on the sides of buildings, window screens and landscaping plants, and
the public may mistake them for giant mosquitoes. In fact, the first reports of
invasive crane flies for both Long Island and the Rochester area were made by
homeowners. High larval densities may also act as nuisance populations as rain
showers can wash them off sloped lawns and amass them as piles of maggots in
affected home lawns and golf course fairways, root pruning leads to white
grub-like damage. The disruption of the rooting zone promotes rapid die-off
when the injured turf is drought-stressed. Another expression of injury is
extreme thinning due to surface feeding. Early to mid-May is when injury is
most likely to be expressed by T. paludosa because large larvae are
feeding rapidly as they approach the end of development. On affected golf
course putting greens, foliar feeding by larvae on crowns and leaf blades
causes damage akin to black cutworms. Larvae will reside in aerification holes
or in self-made burrows from which they emerge to forage, chewing shallow
quarter-sized pits into the playing surface.
detect the presence of invasive crane flies, the leathery pupal cases can be
monitored on tees, greens and fairways where they protrude from the low-mown
turf. At times of peak emergence the adults are abundant and highly visible as
they flit about low in the grass. Adults may also congregate during the day on
the sides of buildings, sliding doors, window screens and fences. Because
adults lay eggs so soon after emergence, they do not move far from the sites
where larvae developed. Therefore, sites with abundant adults, larvae or pupal
cases should be monitored as an indication of sites where eggs of the next
generation are likely to be laid. If a crane fly infestation is suspected, send
adults, larvae or pupal cases to a specialist for proper identification.
signs of insect activity and turfgrass injury suggest leatherjackets, core
sampling is the best way to detect and sample larvae. Larvae can be monitored
in the late autumn or early spring. Take samples with a cup cutter and rip apart
the core to look for larvae. Traditional soap-based disclosing solutions (see
6.2.2) are not effective at driving larvae to the surface. Certain insecticides
such as pyrethroids and carbamates, however, will reveal the presence of larvae
because many will move to the surface before dying, often within 1-12 hours.
This approach is most effective when soil water content is high and
insecticides can readily penetrate the soil surface.
Decision-making. Control tactics
should be directed against the larvae because adults are hard to target and
short-lived. Depending on the overall health of the turf, suggested thresholds
are 15-50 larvae/sq. ft. Autumn populations are likely to surpass these
thresholds, but it is important to keep in mind that leatherjackets can suffer
very high mortality between late autumn and early spring due to winter stress
and predation by birds and other vertebrates. Vigorous turf can therefore
support relatively high population levels in autumn and visible damage is
– Cultural control. Because
of their relative sensitivity to dry conditions, careful manipulation of soil
moisture levels may be a key cultural tactic to reduce populations. Some
strategies might be to regulate the timing and frequency of irrigation,
particularly during the oviposition period, to better drain chronically
infested areas and to allow the sward to dry (i.e., avoiding irrigation) in
autumn. Maintaining a vigorous stand that is more tolerant to infestation might
also alleviate problems.
– Chemical control. The
two main control windows are late autumn and early spring. Since adults of both
species emerge during a similar window in September, small larvae of both
species would be susceptible to preventive insecticides. Therefore a late
autumn preventive application is recommended if populations of both species
occur at the same site. Timing should be after peak emergence of adults in
order to overlap the period of egg hatch and first instars.
applications for T. paludosa can be made in early spring after scouting
has assessed populations or once feeding damage is detected. Tipula oleracea
is probably not susceptible during this window because it pupates early in
spring and insecticides are not active against pupae.
aforementioned control windows, unfortunately, do not coincide with other
turfgrass pests. The arrival and spread of these exotics thereby represents a
worrisome new economic burden for turfgrass managers. To identify the best
chemistries for invasive crane fly control in NY, a series of field efficacy
trials has been conducted against T. paludosa. Based on consistency and
efficacy, a series of chemistries is acceptable for preventive late autumn
control, including bifenthrin, carbaryl, chlorantraniliprole, imidacloprid,
indoxacarb and trichlorfon. Among the best products for curative spring control
are carbaryl, chlorpyrifos, imidacloprid and trichlorfon. Overall, insecticidal
efficacy declines from autumn to spring as the larvae grow larger.
– Biological control. In addition to registered chemical insecticides, a
registered biological control option is Beauveria bassiana, an
entomopathogenic fungus. The entomopathogenic nematode, Steinernema
carpocapsae, is another biological alternative that has been promoted in