Vermont Garden Journal: Preventing Squash Vine Borer Infestations

Jul 20, 2016

We've all lost beautiful summer squash, pumpkin or winter squash plants to the Squash Vine Borer. This destructive moth lays eggs in July at the base of these plants and the larvae burrows into the stem causing it to wilt.

Here are some ways to clear out an infestation and prevent future ones:

Get Rid Of The Larva

  • Physically remove the larvae. Use a sharp knife or razor slit the stem at the hole going away from the base of the plant. Find the fat, white larvae and remove it.
  • Cover the slit with soil and water and hopefully the vine will re-root and survive.
  • Inject Bt organic pesticide into the stem with a syringe where you think the larvae is tunneling. The larvae will eat the Bt and die.

Prevent Infestations

  • Plant resistant squashes, such as butternut.
  • Cover young plants with a floating row cover until flowering. After flowering, cover just the base of the plant with row cover to make a barrier to prevent egg laying.
  • Delay planting zucchini and summer squash until early July to avoid the egg laying stage.
  • Set out a small yellow pail with water in June to trap the moth. They're attracted to the yellow color and drown in the water.
  • Remove infested plants and rotate crops each year.