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Has this happened to your petunias or geraniums?

Has this happened to your petunias or geraniums? Punctured flower buds, devoured flowers, and leaves punched full of holes on your geraniums, nicotiana, and petunias are sure signs that the plants are infested with tobacco budworms (Heliothis virescens), also known as geranium budworms. These caterpillars have become such a serious problem in many parts of the West that by midsummer most blooms either fail to open or have been partially or entirely eaten before gardeners have a chance to enjoy them. (If you garden under oak trees, your plants may also be infested by various leafrollers.) Overwintering in the soil as pupae, the insects emerge in late April or May as night-flying gray moths to lay eggs on the undersides of leaves. Small green caterpillars soon hatch and migrate to buds and leaves, where they feed. This cycle may recur up to five times in a growing season. The first signs of an infestation are tiny holes in the leaves, dark droppings near the holes, and punctured flower buds that don't open. Open one of the buds; you'll probably find a 1/4-inch-long caterpillar feeding. Mature caterpillars reach 1 1/2 inches long and feed on open flowers and leaves. They can be difficult to spot; one of their mechanisms of camouflage lets their bodies take on the color of what they've recently eaten. And they can adopt a variety of colors--from the red of geranium flowers to the greens of different foliage. To control budworms, inspect the foliage and flowers closely and pick off insects and damaged buds where caterpillars may be hiding. At the first sign of damage, spray both the tops and the undersides of the leaves with the bacterial insecticide Bacillus thuringiensis, sevin, or a systemic insecticide containing acephate. Repeat if plants become reinfested.

PHOTO : Well-fed budworm at far left lounges on a petunia flower it hasn't quite finished

PHOTO : devouring. At near left, perforations in nicotiana flower bud indicate infestation
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Copyright 1988 Gale, Cengage Learning. All rights reserved.

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Date:Jun 1, 1988
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