Squash vine borer
A white grub tunnels inside squash and pumpkin stems, so vines suddenly wilt; look for sawdust at the base.
What you'll see
- A runner or the whole vine wilts suddenly, first in the midday heat.
- Holes near the base of the stem, with greenish, sawdust-like waste pushed out.
- The stem feels mushy, and when split open it holds fat white larvae.
Why it happens
An orange and black, wasp-like moth lays eggs on squash stems in early summer. The larvae bore inside and feed for about a month, then drop into the soil to spend the winter.
How to fix it
- Slit the stem lengthwise above the entry hole with a sharp knife, and remove the larvae.
- Heap moist soil over the cut and over a few leaf joints along the vine so it roots again.
- Pull and bin vines that collapse completely, along with any larvae.
Keep it from coming back
- Wrap the lower stems with a foil collar while the moths fly in late spring and early summer.
- Grow butternut squash, which borers rarely attack, and plant squash in a new spot each year.
- Till lightly in late winter and remove dead vines, to destroy the cocoons in the soil.
Sources
- University of Maryland Extension: Squash vine borer on vegetables
- Clemson HGIC: Cucumber, squash, melon and other cucurbit insect pests
General guidance, not a diagnosis. For valuable, edible or outdoor crops, check with a local extension service or plant expert. Use any product exactly as its label says, and keep children and pets away while it dries.