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Imported Cabbage Worm - Pieris rapae   Whitney Cranshaw, Colorado
State University, www.ipmimages.org
  Clemson University, USDA Cooperative Extension Slide Series, www.ipmimages.org  HOSTS: Broccoli and other cabbage
family plants (cabbage, cauliflower, brussels sprouts, kohlrabi, kale), lettuce, radish, rhubarb. DESCRIPTION:
Larvae
are velvety-green with a faint yellow stripe up to 1-1/4 inch long.
They are very slow moving. Adults are white butterflies. LIFE
CYCLE: The adult
butterflies are usually active during the months of May and June.
Larvae hatch and begin feeding, usually on the outside leaves. CONTROLS:Cultural: Grow resistant varieties if available. Heavy rainfall helps to decrease worm populations, so overhead irrigation or directed sprays of water can somewhat decrease population levels in the early stages. Biological: Start checking for these worms as soon as you begin to see adults flying around your plants. Spray with Bt when you find 1 worm per 2 plants. It is most effective on newly hatched, smaller (1/2 – ¾”) worms. See Bacillus thuringiensis. |
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