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.
Emergence Times - Billbugs overwinter as adults and emerge in April or May. In late May, females lay eggs in lawngrass 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. These over-winter starting in October in leaf litter.