Squash vine borer

Adult

UMN Extension (Minnesota): adult is a day-flying moth that mimics wasps; about 1/2 inch; orange abdomen with black dots; first pair of wings metallic green; hind pair clear, often folded at rest. Identification. Not a beetle. Pumpkin is named on that sheet — not claimed as a keyword on this page.

Eggs and larvae

UMN Extension (Minnesota): eggs flat, brown, about 1/25 inch, laid singly at the base. Hatch about one week. Larvae white or cream with brown heads, to almost an inch; bore into stems. Active mid-June through July. One generation per year; larvae overwinter in the soil. Minnesota calendar. Not a national flight.

Hosts and signs

UMN Extension (Minnesota): feeding inside vines and crowns of summer squash, winter squash, and pumpkins. Yellowing of leaves and wilting. Cucumbers and melons less frequently affected. Hosts and signs as observation. Wilt alone is not a diagnosis. Cucumber and pumpkin keywords are not claimed.

Limit

Minnesota squash-vine-borer sheet. Identification, Minnesota timing, hosts, and signs. Not a prevention promise. Stem-cut, Bt, and traps not collected.

Row cover

UMN Extension (Minnesota): row covers to exclude squash vine borers until plants begin to flower. Several cucurbits listed as relatively tolerant, including cucumbers, melons, and squash or pumpkins in Cucurbita moschata. Summer squash is very susceptible. Minnesota sheet. Row-cover-until-flowering and named tolerance. Not a prevention promise. Stem-cut, Bt, and traps not collected.

Limit

UMN common-insects sheet. Row-cover-until-flowering and named tolerance only.

Look

Wisconsin Horticulture (Wisconsin): day-flying clearwing; wasp-like. Forewings greenish-brown; hindwings transparent with reddish-brown fringe. Wingspan 1–1.5 inches. Body rusty orange with black bands. Larvae pale, segmented, dark head, up to 1 inch. Eggs small, brownish, at the base; hatch 7–10 days; feed 14–30 days. Light brown sawdust-like frass. Wilt may be confused with bacterial wilt or Fusarium — look for entrance holes near the base. Identification, signs, and differential. Not a save-the-plant protocol.

Limit

Wisconsin squash-vine-borer article. ID, signs, and wilt differential. Not a survival claim.

Look

Wisconsin Horticulture (Wisconsin): moth ¾–1 inch, 1–1½ inch wingspan; metallic greenish-black forewings; clear hindwings; orange-and-black hind legs. Eggs flattened, oval, dull-red to brown, laid individually. Hatch 7–15 days. Larva cream, wrinkled, brown head. Rarely in cucumbers or melons. Cannot complete development except in summer squash, winter squash, or pumpkins. Separate URL from the Wisconsin squash-vine-borer article. Egg color versus UMN brown stays in Sources differ.

Limit

Wisconsin Melittia cucurbitae article — a second URL, own card. Identification and host notes. Not a cucumber-pest page.

Stages

Maryland Extension (Maryland): eggs tiny brown flattened ovals, attached singly. Larvae wrinkly, white to cream, hairless, up to 1 inch, dark head. Pupa dark brown, shiny, tapered; cocoon black, rough. Adult fat, black, clear-winged moth with orange legs and orange-and-black abdomen; appears similar to a wasp. Overwinters as pupa about 2 inches under soil. 1–2 generations a year. Maryland geography. Generations 1–2 versus Minnesota one stay in Sources differ.

Hosts and signs

Maryland Extension (Maryland): hosts summer and winter squash and pumpkin; very rarely cucumber, gourd, melon. Frass: greenish-white sawdust out the entrance hole; stem near hole feels mushy. Frass color versus Wisconsin light brown stays in Sources differ. Cucumber, gourd, and melon keywords are not claimed.

Limit

Maryland squash-vine-borer vegetables sheet. Stages, hosts, and signs. Not a prevention promise.

Signs

Maryland Extension (Maryland): wilted leaves or vines; hole at the base or lowest 8 inches; sawdust-like frass. Row cover or insect mesh when seedlings emerge; remove during bloom for pollination. Bacterial wilt: leaves recover at night then wilt again — different pattern on that key. Signs plus row-cover-until-bloom. Not a prevention promise. Not a survival claim.

Limit

Maryland squash-problems key. Signs, row-cover context, and bacterial-wilt differential. Not a save-the-plant protocol.