Squash bugs on pumpkin and winter squash

Squash bugs are the most difficult-to-control cucurbit pest in the eastern US. Adult squash bugs are heavily armored, odorous when disturbed, and resistant to most contact insecticides. They inject a toxic salivary compound while feeding that blocks plant vascular tissue, causing rapid wilting and.

Squash bugs are the most difficult-to-control cucurbit pest in the eastern US. Adult squash bugs are heavily armored, odorous when disturbed, and resistant to most contact insecticides. They inject a toxic salivary compound while feeding that blocks plant vascular tissue, causing rapid wilting and collapse. By the time a plant shows wilt symptoms from squash bug feeding, the damage has progressed beyond what insecticide control can reverse.

I don't grow cucurbits at my Long Island property, so this guide draws on Cornell Cooperative Extension, Penn State Extension, and Clemson HGIC research.

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The pest

The squash bug (Anasa tristis) is in the order Hemiptera, family Coreidae. Per Cornell Cooperative Extension, squash bugs:

• Adults: 0.5–0.75 inch (12–18mm), flat, oval, brownish-gray with orange-brown markings on the abdomen edge; they emit a distinct unpleasant odor when crushed
• Eggs: oval, bronze to brown, laid in clusters of 12–20 in a neat chevron pattern on the undersides of leaves (typically at the junction of two leaf veins); egg masses turn from shiny to dull bronze as they age
• Nymphs: pale green-gray, progressing through five instars; first instars have green abdomens and red heads and legs; older nymphs progressively turn gray

The squash bug feeds primarily on pumpkin and winter squash; summer squash and zucchini are moderately susceptible.