Description: Large, green caterpillars with white bars; up to 3 or 4 inches long with a slender horn projecting from near the rear end.
Damage: Hornworms feeds on leaves, consuming large amount of foliage. Leaf loss may result in stunting and fruit scald.
What to do: Handpicking and destruction are often easily accomplished because of size. If large numbers of hornworms or plants are involved, use a recommended insecticide.
Description: Winding white trails or broad white spots appear on leaves, made by small white or yellow legless maggots feeding between upper and lower surfaces of the leaf.
Damage: The leaves may be weakened, and the mines or tunnels may serve as points where disease and decay may start.
What to do: Handpick infested leaves, if practical, before the larvae pupate and begin another generation, or use a recommended insecticide when large numbers of mines are found.
Squash Vine Borer
Description: Thick, white, wrinkled, brown-headed caterpillars, up to 1 inch long. Produces yellowish, sawdust-like excrement from holes in the vines.
Damage: Infested vines are often completely girdled and usually become rotten and die beyond the point of attack. Late in the season, some tunneling in and damage to fruit may occur.
What to do: Plant as early as the weather will allow. With few infested plants, stems can be split and larvae removed. A spade-full of moist soil should be placed over damaged stems to encourage new root growth. Apply a recommended insecticide weekly or as directed by label during the fruiting period.
Description: Slender, up to 1 1/2 inches long. Young borer: creamy white, dark purple band around the body, several brown or purple stripes running lengthwise down the body. Full-grown borer: creamy white to light purple without band and stripes.
Damage: Eats tunnel in stem, causing plant to wither and die. Tunnel usually has opening up to 1/4 inch in diameter at its lower end. Attacks pepper, corn, potato and rhubarb.
Distribution: East of Rocky Mountains.
What to do: Remove and destroy weeds; the insect breeds in weeds, especially dock and ragweed. Plant may be saved by puncturing the insect. To locate the borer, split the stems lengthwise above opening to tunnel. Bind split stem and keep plant watered.
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