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.
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.