Billbugs are a particular problem of Kentucky bluegrass lawns. Members of the weevil family, the adults have long snouts that end in a set of mandibles. Adult billbugs are 1/4 to 1/2 inch long and brown or gray. The larvae do the most damage to the stems of grass plants, however adults will also cause some stem and leaf blade damage. The larvae are small legless white grub-like creatures with a yellow-brown head. They look much like a grain of puffed rice. They feed on stem tissue causing infested shoots to turn brown and die. Billbugs over-winter as adults and emerge in April or May. In late May, females lay eggs in lawn grass stems above the crown in May and June. In June, larvae move into the soil and feed on roots and rhizomes. They remain near the soil surface feeding near the thatch layer when it’s moist. As soils dry, they go deeper. In July, adults appear. Proper identification and treatment are needed when dealing with these insects, in order to maintain effective control.
Chinch Bugs are not as common as some other turf-feeding insects such as grubs or sod webworms, but left unidentified and untreated they can devastate a lawn very quickly. The pests are so small and inconspicuous that they can destroy a lawn right beneath your eyes without being noticed. Chinch bugs cluster in lawns down among grass blades near the crowns of the grass plants and suck juices from their tissues. Their feeding causes grass to appear yellowish and sometimes stains the grass red. These bugs thrive in hot, dry weather, becoming active when temperatures are in the high 70s, and causing most of their damage from August to September, when Northern grasses are stressed from the summer heat. Lower than average temperatures plus moisture retards chinch bug activity. Topical insecticides, combined with regular monitoring are needed to properly control them.
Grubs are perhaps the most hated pest insect in the country. “Grub” is a catch-all term for the larval, or worm, stage of many kinds of beetles. May beetles (also called June bugs), Japanese beetles, masked chafers, billbugs, etc are all grubs in the soil prior to emerging as beetles during the growing season. Grubs are plump whitish colored worms that grow 3/4 to 1-1/2 inches long. They have 3 pairs of legs and tan heads with large, brown-black mouth parts. They rest in a characteristic C-shaped curl just under the soil surface in planted areas or turf, where they feed on roots of ornamental plants and lawn grasses. Grubs are a subsurface feeding insect and therefore must be treated with the correct insecticide in order to establish control. They are often blamed for many lawn problems in error. Grubs emerge from underground and feed only during certain periods of the year, but many blame any browning in their lawn on grubs regardless of the time of year. That is why a correct diagnosis and then sub sequential proper treatment plan should be developed, rather than making incorrect assumptions. The best plan is prevention. Since grubs primarily feed during the fall months, a preventative can be applied late in summer to ensure effective control the entire fall.
Sod Webworms—are one of the regions “silent killers”, as their damage often goes unaccredited to them. Most of their damage is blamed on drought stress or on grubs, but in reality these tiny little caterpillars are quietly feeding on the lawn. In their caterpillar stages, sod webworms are serious pests of lawn grasses. The caterpillars are about 3/4 to 1 inch long. The adults are buff-colored or grayish-brown moths with a wingspan of about an inch. These adults fly in the early morning or late evening in a jerky zigzag pattern, just a few feet above the lawn. They fly up from their hiding places when tall grass is mowed or shrubbery is disturbed. Sod webworm moths do not feed on lawn grasses, but they do drop their eggs into the grass as they fly. After 6 to 10 days, the eggs develop into very hungry caterpillars. These immediately begin feeding on grass blades, and are active only at night. As they feed, they build silk-lined tunnels in the thatch near the soil surface. During the 35 days or so that the webworm lives as a caterpillar, it can eat about 4 square feet of grass. By late fall the webworms are nearly mature. They over-winter curled up in the soil as pupae and emerge as moths in the spring to begin feeding and laying eggs as soon as the soil temperature rises-in late April to early May. First generation larvae feed from late June to the end of July. The second generation can be a more serious problem because the host grasses are usually dormant or under stress and can’t replace damaged foliage. Sod webworms may produce up to 3 generations a season, generations overlapping and having all life stages—eggs, caterpillars and moths—present in the lawn at the same time. Damage will really show itself during hot, dry periods. Correct diagnosis, proper management and regular watering are needed to ensure their damage does not get out of hand.