June 24, 2008
Posted: January 19, 2009
Paul Heller, Professor of Entomology, PSU
TURFGRASS INSECT UPDATE – June Scouting Report
ARMYWORMS (AW) INVASION
I received reports of AW caterpillars invading golf course roughs at select locations in SE and SW Pennsylvania during the week of June 16 which resulted in severe larval feeding damage to turfgrass roughs (see Image One below). AW larval populations were very high. AW larvae feed almost exclusively on grasses and are especially abundant in damp situations. Larvae usually prefer to feed at night; hence AW caterpillars may inflict major injury to turfgrass before being detected. This insect also is a pest on corn and small grains. Occasionally large numbers of larvae develop and move army-like from a devastated area to new fresh foliage. Mature larvae can grow to a length of 1.5 to 2.0 inches. The caterpillars are yellowish to grayish, more or less tinged with pink. The larva’s dorsum is greenish brown to black, with a narrow, broken, light median stripe. A dark stripe includes the spiracles in the lower edge. Armyworms usually do not overwinter in PA and must migrate northward from southern states in the spring. In North Carolina armyworm adults start to appear in May or June. Each adult female can lay up to 2,000 eggs in small clusters or rows on the leaf sheaths of grasses. Larvae emerge in 6-20 days, drop to the ground and feed for 3 – 4 weeks.
The University of Nebraska has an excellent web site which includes a description of an armyworm larva at http://entomology.unl.edu/charts/armywcht.shtml . Adult moths are light tannish to reddish brown. A very distinctive diagnostic characteristic is the presence of a small conspicuous white diamond-shaped dot in the center of the forewing. You can view images of adults by going to BugGuide at http://bugguide.net/node/view/10901 . Look for the diamond dot!!
BLACK TURFGRASS ATAENIUS (BTA)
Early larval instars of second generation BTA were collected on June 23 in Mifflin County from golf course turfgrass. Over the past several years BTA has resurged to become a significant pest of golf courses. 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.
These brown to black, elongated insects, with a pair of large forceps located on the end of their abdomen appear to be abundant as a result of optimum weather conditions. Frequently they are being observed in the turfgrass environment and surrounding areas. This insect is considered a nuisance pest.
JAPANESE BEETLE (JB)
Adult JB’s (refer to Image Five) were first observed on June 21 at the Valentine Turfgrass Research Center. 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.
NORTHERN MASKED CHAFER (NMC)
Adult NMC beetles were first collected in our black light trap located at the Valentine Turfgrass Research Center on June 24. 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 23. 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 (refer to Image Six), 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. Adult SW can be surveyed with a light trap since they are active at night. Pheromone traps are available for this turfgrass pest.