Insect identification > Hemiptera > Squash bugs

Squash bugs

The squash bug (Anasa tristis De G.). - The squash bug is common almost everywhere in the United States, feeding on squash and pumpkin and sometimes on cucumber and melon plants. The adult is a dark-brown bug, very finely mottled with gray or lighter brown in many cases, about three-quarters of an inch long. It winters as the adult under rubbish or in other protected places, and appears in spring, ready for its food plants when these come up. When the leaves of the plants develop, the bugs lay their eggs on their under surface in clusters which vary greatly in the number of eggs composing them.

The eggs themselves are oval in outline, very convex, and being resin brown in color are very conspicuous against the green background of the leaf. In a cluster the eggs are not usually so laid that they touch but are somewhat spaced apart in most cases. At intervals before and during the egg-laying period the adults feed on the plants and when they are very abundant may seriously injure or in some cases even kill them.

The eggs hatch on an average in about 10 days and the tiny nymphs, green and reddish in color, begin to suck the sap from the under side of the leaves, at first together, but scattering later. The reddish color of the nymph quickly changes to black and the green gradually becomes more of a gray. Feeding and molting five times results in the production of the adult after a period of from 4 to 5 weeks from the time the eggs hatch, and in the North the adults feed on the plants until fall; then they go into winter quarters. In the South the longer seasons which permit an earlier start in the spring and the higher temperature which causes the eggs to hatch more quickly permit the production, in some cases at least, of two generations each season.

The injury to the plants caused by the spring feeding of the adult is continued by the sucking of the young. Where these are plenty, growth is checked and the crop reduced. If the plants are killed by frost before the nymphs are mature, they often attack the fruits in order to obtain the nourishment they need to become adult.

Control. - Contact insecticides are not effective for the adult squash bug, which has an unusually thick shell. The usual methods for control are the removal as far as possible of all rubbish and places where the insects can obtain protection during the winter; stimulation of growth of the plants by fertilizers and cultivation; protection of the young plants by fine netting until they are so well started that they can thrive despite the bugs. Egg masses being easily seen can be quickly found and crushed.

In the South one or two very closely allied species also attack the squashes and cucurbits and may be controlled in the same ways.