General Turf Insects – Thatch and Soil Pests David J. Shetlar, Ph.D. The “BugDoc” The Ohio State University, OARDC & OSU Extension Columbus, OH John Royals CPCC

White Grub Damage

Annual White Grub Species Masked Chafers (North America - N, S, SW, W, SE) Japanese Beetle (eastern NA) Oriental Beetle (northeastern NA) European Chafer (northeastern NA) Asiatic Garden Beetle (northeastern NA) Green June Beetle (south-transition NA) May/June Beetles (southern only)

White Grub Adults Annual Grubs GJB, EC, SMC, NMC, JB, OB, AGB Multi-year Grubs, M/JB Multi-gen/yr Grub, BTA

White Grub Third Instars Annual Grubs GJB, EC, MC, JB, OB, AGB Multi-year Grubs, M/JB Multi-gen/yr Grub, BTA

Identifying Grub Species Identify grubs by raster pattern Adults are easy to ID but they don’t predict grub populations! Japanese beetle has V-shaped pattern.

White Grubs (Scarabaeidae) Very large family of beetles (over 12,000 species world wide) Adults are beetles Adults of many species are leaf feeders (Japanese beetles) Adults of some species do not feed at all (Masked chafers) Larvae are C-shaped (scarabaeiform) White Grubs, with a sclerotized head and prominent mandibles

White Grubs (Scarabaeidae) Larvae of many species live in soil and feed and feed on roots Development of larval stages is progresses from egg through 3 larval instars Last period of time spent in the third instar is a non-feeding stage called the pre-pupa Third instar larvae often the most destructive stage due to size and duration

White Grubs (Scarabaeidae) Field Identification Use a magnifier to see rastral pattern Parts of rater: septula- median longitudinal bare area, palidium- the rows of spines (pali), anal slit Eggs readily visible to unaided eye when deposited, shiny white, absorb moisture from the soil as the embryo grows

White Grubs (Scarabaeidae) Damage Most serious pest of cool season grasses, but feed on the roots of all species of currently used turfgrasses Difficult to control because subterranean habitat requires control measures that can penetrate the soil Seasonal aspect related to the life cycle of the grubs, one year life cycles (Japenese beetles and chafers) cause damage that is manifest usually in late summer and early fall after the grubs reach their third instar In winter, grubs move deeper in the soil unlessed forced upward by excessive rainfall In spring they return to the soil-thatch interface to feed for a short period (however feeding in spring can be vigorous enough to cause severe damage)

White Grubs (Scarabaeidae) Generalized seasonal histories and habits White grubs have either one generation per year or a generation that requires 2, 3, or 4 years to complete, with 3 the most common The black turfgrass ataenius is an exception it has 2 generations per year Adults may be nocturnal or diurnal Adults deposit eggs in moist soil or soil- thatch layer

White Grubs (Scarabaeidae) Generalized seasonal histories and habits Young grubs feed on fine roots and exhibit quite extensive capabilities for vertical movement Vertical movement governed by soil moisture and temperature Cold temps they move down, warm up Wet they move up, dry down Upward spring migrations occur when soil warms sufficiently for the species

White Grubs (Scarabaeidae) Generalized seasonal histories and habits When larval feeding in the 3 rd instar is complete, grub migrates downward to form an earthen cell Prepupal stage lasts only a few days prior to pupation At appropriate time, adults dig their ways to the soil surface

Japanese Beetle – Japanese beetle adult skeletonizing leaf Mating cluster of beetles in turf

Japanese beetle distribution (2000)

Japanese Beetle Life Stages egg 1st 2nd 3rd pupa adult instar larva

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Japanese Beetle Annual Cycle

Japanese Beetle Most wide spread and serious pest in the Northeast through Mid-Atlantic region Adult also a major pest in landscape settings (300= host plants) where turfgrass is extensively used Adult brilliant metallic green with copper colored elytra that do not entirely cover the abdomen Damage by adults is skeletonization of leaves; extensive feeding can lead to defoliation When adults emerge from the soil they go back and forth to their tunnels, leaving them on clear mornings for feeding and mating (diurnal activity), returning in the late afternoon; on cold wet days, remain in soil

Japanese Beetle Mating occurs on host plants, frequently; females mate between each oviposition period Mated females burrow into soil and deposit eggs; may do this 16 or more times during her life to deposit eggs (aggregate); prefers to deposit eggs in short-cut turfgrass and pastures Eggs hatch in 2 weeks; new larvae are creamy white, but like the other scarabs, after feeding starts the accumulation of fecal matter in the hindgut makes them appear gray to black

Japanese Beetle Rastral pattern has a characteristic V- shape in the palidia and a transverse anal opening Grubs develop to third instar in 6 or 7 weeks; feeding vigorously in September and October One-year life cycle

Masked Chafers – Pair of masked chafers at night on turf Masked chafer eggs newly laid (below) 48 hours in moist soil (above)

Identifying Grub Species Masked chafers have no pattern!

Northern Masked ChaferSouthern Masked Chafer Southwestern Masked ChaferWestern Masked Chafer Masked Chafer Distribution Maps

Northern Masked Chafer Life Stages egg 1st 2nd 3rd pupa adult instar larva

Masked Chafer Annual Cycle

Northern and Southern Masked Chafers Yellow-brown color and have chocolate-brown heads that shade to a lighter brown clypeus Grubs of both species are important in their geographical ranges, causing extensive damage to cultivated turf in late summer and early fall Masked chafer grubs are more inclined to feed on organic material in the soil than other grubs, so usually larger populations are needed to cause turf damage Adults do not feed

Northern and Southern Masked Chafers Raster has no particular pattern; anal slit is transverse One- year life cycle Adults emerge and fly beginning in June, and flight activity is greater following a rain Adults are nocturnal and can be detected in light traps Male searching and mating occur on the sod surface

Northern and Southern Masked Chafers Eggs are deposited in the soil; egg stage lasts 2- 3 weeks, after hatching, feeding begins almost immediately by the grubs Grubs grow quickly and reach their full size of about an inch by late August Third instars damage turf in September and October until they are forced down into the soil In spring, they return briefly to near the soil surface (March) but then return deeper to pupate prior to adult emergence in June

Green June Beetle – Adult Mature grub “crawling” on soil Grub in overwintering burrow Overwintering Japanese beetles

Identifying Grub Species GJB crawls on back!

Green June Beetle Distribution

Green June Beetle Nominal importance as a turf pest primary damage is mechanical disruption of soil caused by the burrowing in and out of the soil and producing mounds Prefers soils high in organic matter Adults feed on and injure ripening fruits with thin skins( peaches, etc) active throughout the summer from the time of emergence in June

Green June Beetle Adult activity on turf is diurnal, mating occurring in morning and late evening, returning to turf where they burrow in for the night, creating little mole-like burrows just beneath the grass Oviposition in July and August Eggs hatch in 2 weeks Grubs reach third instar during the fall and overwinter; resume feeding in early spring

Green June Beetle Grubs have an unusual means of locomotion they craw on their backs; leave burrows at night; reenter to spend the day; this burrowing creates mounds of earth much like ant hills One year life cycle

European Chafer – © H. Niemczyk European chafer adults swarming to tree at dusk for mating Adult

Identifying Grub Species European chafers have Y-shaped anus & two rows of bristles that diverge at anus. Y-shaped anus with two rows of bristles.

European Chafer Distribution (2000)

European Chafer Life Cycle

European Chafer More serious than Japanese beetle where it occurs (New York and Vicinity) Rastral pattern with sub-parallel rows converging anteriorly and curving outwardly posteriorly, Y shaped anal slit One year life cycle with inordinately long period in third instar

Oriental Beetle & Asiatic Garden Beetle – Three common color forms of Oriental beetle Asiatic garden beetles feeding & mating

Identifying Grub Species Oriental beetle has two rows of small spines, in number. Asiatic garden beetle has vertical anus & broad U-shaped spine pattern.

Asiatic Garden Beetle (2000)Oriental Beetle (2000) Oriental Beetle & Asiatic Garden Beetle Distribution Maps

Asiatic Garden Beetle Isolated but increasing distribution One year life cycle Rastral pattern of grubs a single transverse row of spines in crescent shape Adults have nocturnal habits

Black Turfgrass Ataenius (& Aphodius)

Identifying Grub Species Ataenius raster is random pattern of bristles and anal pads separate. Aphodius raster has small V pattern and anal pad is only cleft, not divided.

Black Turfgrass Ataenius Distribution

Black Turfgrass Ataenius Native insect that causes damage almost exclusively to golf courses mostly in the midwest on bluegrass or bentgrass Adult is a tiny black beetle Typically scarabaeid grubs with no distinct rastral pattern A third instar BTA grub may look much like a first instar of other scarabs One or two generations a year Over wintering in leaf litter and roughs around golf courses as adults

Target Principle © HDN

Where do grubs feed? Ans: Soil-Thatch Interface © HDN

What do grubs eat? Ans: THATCH, soil (oh, and roots)

Mole cricket damage to bermudagrass.

Native (northern) mole cricketSouthern mole cricket Tawny mole cricketShortwinged mole cricket

Native Mole CricketTawny Mole Cricket Southern Mole CricketShortwinged Mole Cricket

Mole Crickets In the Carolinas damage is in coastal areas Mole crickets do their damage primarily by tunneling one adult may tunnel 30-40ft/evening Population of more than one per square foot could destroy a tee box overnight Mounds created by tunneling also cause the soil to dry out excessively Tawny Mole Crickets (TMC) also feed directly on the root system

Mole Crickets Bahia and bermuda are most susceptible but damage occurs to all warm season grasses Mole crickets prefer light soils (light sand to loam soils that are compressible enough to allow tunneling)

Mole Crickets Separation of TMK and SMK TMK feeds primarily on plant material and Southern Mole Cricket (SMK) feeds mostly on other insects Damage due to TMK is by tunneling and feeding and by SMK by tunneling only TMK is slightly larger and lighter in color than SMK SMK has 4 light spots on thorax

Mole Crickets Separation of TMK and SMK SMK has open, rounded gap between dactyls; TMK has narrow v-shapped gap Both spp. Have similar life cycles (one-year generation Both spp. Overwinter as adults and nymphs Spring mating flights are main periods for both spp. But TMK begins flight period a little earlier (March) Adult flight activity ends in June

Mole Crickets Life Cycle After mating, eggs are laid in little chambers off to the side ogf burrows Each female excavates three to five chambers and deposits about 35 yellowish eggs in each of them When the eggs hatch, the young start feeding on unhatched eggs and each other Many are lost to cannibalism The nymphs develop throughout the summer Adults are present in September

Mole Crickets Activity During the day activity of mole crickets is stopped They stay in permanent burrows At night, they start tunneling and feeding at or near the surface TMK does more root feeding and is therefore a more serious problem than SMK The SMK eats mostly other insects, including other mole crickets

Mole Crickets Sampling and Monitoring Soap flushes are effective Threshold population densities vary with time and place of occurrence (0 for greens)