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Corn Ear Worms - Heliothis zea     HOSTS: Beans, corn, peppers, tomatoes. DESCRIPTION:
Adults
are light gray moths with dark, irregular lines on their wings. Larvae
are 1/8 to 1- 1/2 inch long; they are yellow/white to green with brown
heads and longitudinal white bands. LIFE
CYCLE: Adult
moths usually cannot overwinter in Montana. They migrate from the south
and arrive in June or July. The moths lay eggs on or near the silks of
corn. On other vegetable crops, eggs are laid on leaves near the
developing fruits. After 2-5 days, larvae hatch and tunnel into the
ear. Four weeks later they are ready to pupate in the soil. Pupation
takes 10-14 days. There are generally 2 generations a season. CONTROLS:Traps: Blacklight traps catch male and female moths; pheromone traps catch only the males. Both traps are most effective as indicators of population levels. Mechanical: Use floating row covers, being sure to remove them when plants bloom so that pollination is not hindered. (Remay has been shown to be the most effective type of floating row cover for these types of pests.) Biological: Scout your plants every 2 to 3 days; apply Bacillus thurengiensis (BtK) in granular or ES (emulsifiable suspension) form if 20% of leaves have "shot holes" in them, being particularly attentive to the undersides of the leaves. (BtK is most effective on small larvae, 1/4 to 3/4 inch long, in their first instar.) FOR CORN: Spray directly to leaf whorls, and to silks after they have wilted. Apply BfK or Xentari(dry flowable Bt). For late plantings, apply Xentari once at tassel; hand apply a corn oil/Bt mix directly to corn silks. Apply any of the various horticultural oils to ear tips 4 - 5 days after the silks wilt to discourage worms already present. Botanical: Spray ryania or rotenone/pyrethrin in the evening. NOTE: Minute pirate bugs and damsel bugs feed on eggs. On tomatoes and peppers Bacillus thuringiensis is effective as a spray. FOR CORN: Injecting mineral oil into the silks after silks begin to brown can control caterpillars. |
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