Flightless weevils
From BugwoodWiki
Author: Dr. D. L. Horton, Dr. H C Ellis, The University of Georgia, Department of Entomology.
Contents |
Description
Flightless weevils are typically active at night. Adults hide during the day. When disturbed, they drop to the ground where protective coloration makes them difficult to see. Species of root weevil grubs cannot always be distinguished from one another in the field. All are legless, C-shaped, and white with brown heads.
Hosts
Hemlock, rhododendron and several other ornamental shrubs, as well as strawberry and some greenhouse plants such as impatiens.
Damage
Adult feeding makes notches on the edge of leaves. Adult injury is often minor unless large numbers of weevils are present. The larva feeds on roots and may consume most of the tender roots, causing the plant to die. The diagnosis of dead, wilting, or declining plants should include examination of the roots. Early detection is possible through recognition of adult feeding symptoms.
Life Cycle
All flightless weevils are female. Adults feed for 2 - 3 weeks before laying eggs. During midsummer, the weevil alternately feeds and lays eggs for a month or more. Larva feed from midsummer, when the eggs hatch, into the fall, and again in the spring. Feeder roots and bark on larger roots are consumed by the larger larvae in the spring. Root feeding injury may not cause noticeable symptoms in the nursery, but infested plants may die after they have been transplanted. The grubs may be found around roots at a depth of from 2 - 40 cm in the soil. Pupation occurs near the soil surface. There is usually one generation each year. Partially grown larvae overwinter in the soil. Adult emergence starts about May, and egg laying begins 1 - 2 weeks later. Females lay as many as 500 eggs in the soil near the base of plants over a period of 2 - 3 weeks. The eggs hatch in 10 days to 2 weeks, and the larvae tunnel through the soil to feed on roots. The most extensive feeding occurs in late-May and early-June, just before pupation.
Control
Adults can be controlled by insecticides when diagnosed.
