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July 10 , 2007
Volume 15, No. 2

Christmas Tree and Landscape Pest Management Newsletter

Editor:
Paul Heller, Professor of Entomology, PSU

ISSUE HIGHLIGHTS

*Turfgrass Insect Update – June through Early July Scouting Report
*Update on Status of Chlorpyrifos

TURFGRASS INSECT UPDATE – June thorugh Early July Scouting Report

ANNUAL BLUEGRASS WEEVIL (ABW): This insect caused major damage to Poa annua turfgrass areas on golf course turf during the month of June.  I received a number of reports that ABW damage was excessive at some locations.  Adult weevils normally do not cause damage to annual bluegrass. Adults are ca. 3/16 to ¼ inch long and dark brown to black with a long beak-like snout with knobbed antennae attached near the end.  Plus, the body of the adult is covered with fine, yellowish hairs and scales that wear off with age.  The larval stage of this pest can cause major damage. Larval feeding damage can occur inside the stem (neonate), exteriorly on the stems (mid-size), and base of stems (large-size or ultimate).  ABW larvae are legless, ca. 1/32 inch long when newly hatched and grow to about 3/16 inch long when full grown.  Recently the USGA reported in their Mid-Atlantic regional update that ABW damage was severe in our region.  We recorded an average of 394 annual bluegrass weevil larvae per square foot in untreated checks in our project’s 2007 ABW research studies.  Although ABW larvae are small they can cause significant damage and the latter damaged areas should be ‘mapped’ annually to maintain a historical record regarding where the pest is located.  You can have two generations annually but the first generation usually causes the most severe damage to Poa annua.  In the future please remember to rely on the use of synchronous phenological plant indicators to assist you in determining when to apply a preventive application in the spring.  Synchronous phenological plant indicators can assist golf course superintendents in determining when adult weevils start to move from their overwintering sites in the spring (full bloom of forsythia) and when most adults have moved out into fairways, tees, and greens (full bloom of redbud and flowering dogwood).  Some superintendents start to sample grass clippings collected from the front mowing baskets of greens mowers for adult weevils in the spring prior to full bloom of forsythia and continuing through full bloom of flowering dogwood and redbud.

Larval stage of annual bluegrass weevil.

Feeding damage by annual bluegrass weevil larvae (left side of image) compared to treated area (right side of image)

BLACK TURFGRASS ATAENIUS (BTA): Currently we are collecting early larval instars of second generation black turfgrass ataenius.  This scarab white grub over the past several years has resurged to become a significant pest of golf course turfgrass.  BTA overwinters as an adult (small, shiny black beetle, ca. 3/16 inch long, and ca. 3/32-inch wide) and usually produces two generations annually.  Turfgrass personnel need to become reacquainted with the life cycle of this grub species so preventive applications can be applied at the optimum time.  Once again synchronous plant phenological indicators can assist the superintendent in determining when select life stages and generations will be present which can support them in suppressing this scarab grub pest.

BILLBUGS: Billbug larval damage to turfgrass especially athletic fields and residential lawns was severe in June and continues into July.  We need to remember that we now have two species of billbugs damaging PA turfgrass, respectively bluegrass and hunting billbug.  Previously hunting billbug (HB) was primarily a warm season pest. However, it is now present in our region causing significant damage.  Unfortunately minimal information is available on the life cycle of hunting billbug.  It is interesting to note that Florida entomologists have stated that hunting billbug adults have been found every month of the year, but most activity has been noted in the fall and winter (i.e., in Florida not PA). HB has one generation a year in the northern regions of its range, but because of its extended oviposition period, hunting billbug larvae may be observed throughout the growing season.  Damage may be worse during periods of drought and/or hot dry weather.  Hunting billbug adults (ca. ¼ to 7/16 inch long) are slightly larger than bluegrass billbugs.  Adults usually are charcoal gray to black with numerous punctuations on the pronotum and a distinct Y-shaped smooth raised area just behind the head.  The latter area is enclosed by a shiny, parenthesis-like mark on either side.  HB larvae are 3/8 inch long when mature, thickest at the middle with a white to yellowish body, legless, the head tan to brown, and mandibles mostly black. We recorded an average of 24-40 billbug larvae per square foot in untreated checks in our 2007 Penn State billbug research studies.

Larval stage of hunting billbug

Adult hunting billbug

EUROPEAN CHAFER (EC): We received a report from a home owner located in Northampton County of European chafer adult activity in mid-June. Adults are light reddish-brown beetles, about 9/16 inch long, with a slightly darker head and pronotum.  The trailing edge of the insect’s pronotum has a narrow band of light yellow hairs, while the underside of the thorax is covered with pale yellow hairs.  The tip of the beetle’s abdomen extends beyond the wing covers.  Also wing covers have distinguishing longitudinal grooves and minute punctuations.  The mating flights consist of numerous EC adults and have been described "to sound and look like a swarm of bees." The flights usually occur at sunset when enormous numbers of adult beetles swarm about a tree or tall shrub, or even sometimes a chimney, for about 30 minutes, and then settle down on the foliage where mating occurs. Adult beetles may ‘nibble’ on the margins of tree leaves, but normally do no real damage and they do not bite or sting. The following day females will burrow into the soil a few inches and deposit eggs in earthen cells. Generally they lay 20-30 eggs, depositing them singly in cells. Eggs hatch in 14-21 days and the tiny grubs begin feeding. By fall the grubs are in the 3rd instar. The following spring, as soils begin to warm, the grubs again come toward the surface and feed. The pupal stage occurs during late May and early June. During this stage the insects do not feed. Most European chafers have a 1-year life cycle.

GREEN JUNE BEETLE (GJB): Adults were observed emerging from a home lawn in Mifflin County on July 5, 2007.  Adults are 3/4 to 1.0 inch long with a velvety green and yellow-margined upper surface and shiny metallic green or gold below. They also have a distinct, small flat horn on their head. Legs of the adult have stout spines which aid them in digging.

Most GJB adults spend the night in the soil or under debris. Males are attracted to females by a very strong fluid (pheromone).  GJB females lay their eggs in sandy, moist soil containing decomposed vegetation or well-rotted manure. Eggs are deposited in balls of soil as large as a walnut and held together by a glutinous secretion. Each soil ball may contain 10 to 30 eggs. GJB adult females deposit 60 to 75 eggs over their 14 day egg-laying period. Grubs hatch from eggs in two to three weeks and feeding damage usually is apparent by mid-August. GJB grubs are not capable of walking on their somewhat small stunted legs. Instead, they crawl on their backs by alternate contraction and expansion of their body parts, assisted by posteriorly directed spines.  GJB grubs, especially third instars, come to the surface at night to feed and may at times graze on turf according to Salvaggio and Hellman (University of Maryland). Soil accumulating at the surface resembles earthworm castings. Early instar grubs frequently can be found tunneling in the top four inches of soil. They will loosen the soil and eat or thin out the thatch. Grubs seldom consume enough turf roots to cause significant damage. However, their disruptive burrowing and mound building activities can disfigure turf. The latter mounds frequently are two to three inches in diameter plus, grubs leave distinct open, vertical soil burrows averaging six to 12 inches in depth. The diameter of the burrow is about the size of your thumb. Salvaggio and Hellman (University of Maryland) reported that drought-stressed turf and grass that is maintained at a very short height succumbs easily to this type of damage. Likewise mounds of soil can dull reel-type mowers. 

JAPANESE BEETLE (JB): Adult populations have been very active since the week of June 18 in central PA.  Adults numbers appear to be high based on catches from our traps and visual observations on turfgrass or preferred plant materials.  Japanese beetles are brilliant metallic green beetles, 3/8 to ½ inch long, bearing coppery-brown wing covers.  JB adults have five lateral spots of white hair on each side of the abdomen, while there is another pair of white tufts on the upper surface of the last abdominal segment, located just behind the wing covers.  Emerging beetles feed and mate.  After feeding for a few days, females crawl into the ground and under turf to lay their eggs. Eggs hatch in about two weeks into first instar grubs which will continue to grow and feed throughout the summer and fall.

Adult Japanese beetles

NORTHERN MASKED CHAFER (NMC): We started collecting adult NMC beetles in our black light trap located at the Valentine Turfgrass Research Center on June 20.  These insects are active at night and do not feed as adults.  NMC adults are chestnut-brown, covered with fine hairs, and ca. ½ inch long.  After mating, the females dig into the soil to lay their pearly white, oval eggs.  Eggs hatch within 14-18 days.  This scarab white grub has caused considerable damage to residential lawns and recreational turfgrass over the past five years.

SOD WEBWORMS (SW): Adult sod webworms were first observed flying in Central PA on June 21 and are still flying as of this week.  Adults are dull-colored with wingspans of ca. ¾ to 1 inch.  Adult moths have a prominent ‘snout’ and when at rest the moths often face downward on a grass stem, wrap their wings around the abdomen, and hold their bodies at a 25˚ angle from the stem.  There are several species of SW throughout our region.  Females drop their eggs over turf for ca. 7 to 14 days after mating.  Young caterpillars hatch in ca. five to seven days and construct tunnels of silk enmeshed with soil and grass clippings.  They reside in the tunnels, hiding during the day and emerging at night to feed on grass blades and shoots.  The most evident sign of SW larval feeding is the appearance of brown patches of grass, up to the size of a baseball and sometimes you will observe green fecal pellets or frass.  These patches often are punctured with pencil-sized holes produced by birds searching for the webworm burrows. Full grown larvae are ca. ¾ inch long and brown to green with darker spots.  Most species require four to seven weeks to complete the caterpillar stage.  A complete life cycle usually requires six to 10 weeks.  You can have two generations annually.    Adults SW can be surveyed with a light trap since they are active at night.

Update On Status of Chlorpyrifos!
Please find attached (click here) a letter from DOW AGROSCIENCES™ regarding the company’s Notice of Cancellation of Chlorpyrifos Uses.  Please refer to the attached letter for detailed information on the process.