Carrots: Carrot Weevil

Problem
The upper part of the root is scarred with zigzag tunnels. White, curved, legless grubs, about 1/3 inch long, may be found in the root and soil.

Analysis
(Listronotus oregonensis)

This insect feeds on carrots, dill, celery, parsley, and parsnips. The adult is a dark brown beetle that lays eggs in the carrot tops. In May and June the eggs hatch into white grubs, which travel down to the developing root. Here the grub tunnels into and feeds on the upper tissue, scarring the root. After a short resting period in the soil, the pest emerges as an adult and lays eggs that hatch into a second generation in August. The adults of this second generation spend the winter in debris in and around the garden. The following spring, the cycle repeats itself.

Solution
There are no insecticides currently registered for use on this insect pest. Some control may be obtained when spraying for leafhoppers (see Leafhoppers). Clean up garden debris in the fall to eliminate overwintering spots for the adults. Do not add infested debris to the compost pile.