SQUASH BUG

A. a, the parasite fly; b. diagram of a squash bug showing relative size and location of parasite larva in the host. B. Some of the life stages of squash bug; c, eggs; d. newly hatched nymph; e, half-grown nymph; f, adult. C. Damaged plant; g, egg mass; h, nymphs a few hours old; i. adult. (A and B, about twice natural size.)

SQUASH BUG

The squash bug feeds by sucking the sap from the leaves of squash, pumpkin, and related plants. The leaves it attacks wilt rapidly and become black and crisp, as if the flow of the sap had been cut off or poisoned. Small plants may be killed outright. In older plants only some leaves or runners may be killed.

Only the unmated parent bugs can live through the winter. They hibernate in all kinds of protected places but prefer to hide under piles of boards or in buildings. In the spring, when the plants begin to develop runners, the bugs fly into the garden and lay eggs on the under sides of the leaves. The young, wingless nymphs emerge from the eggs in a week or two and begin feeding. They require about 4 to 6 weeks to reach maturity. There is one generation a year.

Control: Dust with 10 to 20 percent sabadilla seed powder. In small plantings, hand-pick the adults, nymphs, and eggs.

Trap adults under small pieces of board laid on the soil around the plants. Collect and kill trapped bugs each morning.

A tiny tachinid fly (Tricbopoda pennipes) preys on the squash bug and eventually causes its death. The fly deposits its eggs on the mature or nearly mature squash bug. In 3 or 4 days a maggot hatches from each egg. The maggot bores into the squash bug, where it begins to develop when the squash bug matures. Only one maggot develops in each bug. In summer 2 to 3 weeks is required for the maggot to become full-grown. During that time the squash bug continues to live but gradually becomes unable to produce eggs. When it is mature, the maggot bores its way out, finds its way to the ground, and enters the soil to pupate. The squash bug is killed by the emergence of its parasite. The pupal stage of the tachinid maggot ordinarily lasts about 2 weeks. There are several generations a year. If winter sets in, however, the fly passes the winter as a maggot within the body of the squash bug, and does not mature until spring.