Squash Vine Borer and Squash Bugs
Order: Lepidoptera; Hemiptera
Family: Sesiidae; Coreidae
Genus: Melittia; Anasa
Species: M. cucurbitae; A tristis
Squash Vine Borer Squash
Bugs Insects, Animals
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Squash Vine Borer
The Squash Vine Borer is a very destructive pest of winter squash, gourds, zucchini and pumpkins. They are a native pest in the United States east of the
Rocky Mountains from Canada to South America.
The Squash Vine Borer is a caterpillar as a nymph and a moth as an adult. Females lay
their brown eggs on leaf stalks and vines. These eggs hatch ten days
Nymphs are cream colored caterpillars that immediately after hatching, bore into the stems of
the host plant.
They feed for several weeks before moving to the soil to pupate. Nymphs overwinter inside a cocoon made of black silk a few inches below the
surface of the soil and emerge in the spring as a moth.
Adult Squash Vine Borers are dark gray moths with hairy red hind legs, metallic green front wings and clear hind
wings. Males and females are similar, but males are more colorful and have a
narrower abdomen and feathery antenna. Adult Squash Vine Borer moths are active during the daytime and
rest on the leaves in the evenings, which is different from most moths that are active at night.
When caterpillars bore into the stalks as nymphs, they create sawdust like frass
near the base of the plant. They also excrete a brownish yellow liquid that is pushed through the holes in the stem. Because of the
burrowing, the stem begins to wilt and turns wet and shiny. Several borers can cause the plant to split
open and infested hosts will eventually die.
Another major pest of squash and pumpkins is the Squash Bug. They are very
difficult to control in large populations. The Squash Bug causes damage by removing sap from the leaves that cause them to welt and collapse. They can also
cause Yellow Vine Decline in melons, watermelons and pumpkins. The bacteria they
carry is injected as the bug feeds. This results in yellowing and death of the plant.
Squash bugs can emit an unpleasant odor when disturbed. They fly in fields and
gardens from May to June and lay eggs on the undersides of leaves. Eggs are
bronzed colored and football shaped. After two weeks the eggs hatch and dark red
larvae emerge with light green abdomens. Nymphs eventually grow light grey legs.
After six weeks they become adults and spend most of their time on the base of stems. Adult squash bugs are winged, brownish black with gray and light brown
Our thanks to Lani Powell for research and writing which
made this information page possible!
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