Anasa tristis
From BugwoodWiki
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Description
An adult squash bug is oval-elongate, dark brown, mottled with light gray on its back and mottled yellow on its underside. It is 16 mm long and flat across its back. It has piercing-sucking mouthparts.
Photo by Whitney Cranshaw, Colorado State University, Bugwood.org
Nymphs undergo five instars before entering the adult stage and range in length from 2.5 to 10 mm. Nymphs are grayish-white with dark heads, legs and antennae. The last two instars have dark wing pads. Eggs are spindle-shaped and white when first deposited turning to yellow-brown and eventually to bronze. Eggs are laid on the foliage in masses of 20 to 40.
Hosts
All cucurbit vine crops are subject to attack. The bugs prefer squash, pumpkin, cucumber and melons in that order.
Damage
Feeding in colonies, adults and nymphs pierce vines and inject a toxic substance into plants. As a result, vines quickly turn black and dry out. Small plants and individual runners of large vines may be destroyed. When infestations are heavy, fruit may not form.
Photo by Whitney Cranshaw, Colorado State University, Bugwood.org
Life Cycle
Squash bug overwinter as unmated adults under plant debris or other suitable shelter. When cucurbit vines start to run in the spring, squash bugs fly into fields and mate. Over a period of several weeks, eggs are laid on undersides of leaves, typically in the angles formed by the leaf veins. One or two weeks later, nymphs hatch. Four to 6 weeks pass before nymphs develop into adults. Because of the prolonged development period, nymphs and adults may be present throughout the summer. Feeding continues until frost forces adults into hibernation.
Control
Squash bugs can be difficult to control, however, not impossible. Good cultural practices help prevent squash bug damage. Vigorous, healthy vines can withstand some infestations. Destruction of crop residues after harvest is helpful. On young plants look for immature squash bugs near the base of plants.
