Field Identification
The larva of a clearwing moth that bores into squash and pumpkin stems (and sometimes melons), often killing vines when tunnels girdle the plant. Look for sawdust-like frass at the base of stems, wilting that does not recover overnight, and entry holes near soil level.
Adults resemble small wasps: orange and black with clear wings. Cream-colored larvae with a dark head tunnel inside stems. One generation is typical in the North; multiple generations occur in warm regions.
How to Deal With It
Organic Control Methods
Time plantings to avoid peak egg-lay, use floating row cover until flowering (then remove for pollination), and rotate cucurbit locations. Destroy crop debris at season end.
Encourage generalist predators and parasitoids; soil-dwelling beneficial nematodes (e.g., Steinernema spp.) applied against pupae can reduce next-season pressure where labeled for organic use.
Choose parthenocarpic or bush types under cover when possible; hill soil around stems to encourage adventitious roots past damage; trap crops of very attractive squash can pull egg-lay away from main plantings.
Slit stems carefully to remove larvae with a knife, then bury or pack moist soil over wounds. Crush eggs on stems and petioles. Yellow sticky traps help monitor adult flight.
Bt kurstaki has limited reach to borers inside stems; neem or kaolin on stems and leaf undersides may deter egg-laying if reapplied after rain. Focus sprays on the lower stem during adult flight.
Let Nature Handle It
Natural Enemies
- Braconid Wasps
- Ichneumonid Wasps
- Beneficial Nematodes
Threat Map