Preventing Squash Vine Borer

After planting, tenting the plants with a floating row cover will prevent the adult moths from laying eggs on the vines. When the plants begin to flower, the row covers must be removed so the bees can pollinate the plants or you may choose to hand pollinate by gently smooching a male flower into the face of a female flower.
A floating row cover is made of lightweight spun polyester. Air, sun and water move through it, but the squash vine moth can’t get to the plants to lay their eggs. Be sure to anchor it well so the wind doesn’t carry it off and the moths don’t crawl under the sides. 

The moths lay eggs singularly along the vines, usually from the last week June to early July. The eggs look like small rust red dots. Flicking them off with your nail will take care of the problem, but it’s tough to get them all. Most of the eggs will be laid within a couple of inches of were the stem of the vine emerges from the soil. Carefully wrapping the vine with tin foil at that point will help prevent the moth from laying her eggs. The reflection from the silver foil also confuses the moth and hopefully she will move on.

To monitor the activity of the squash vine borer moth in the garden set out a couple of yellow traps in the vicinity of vulnerable plants: summer squash, winter squash, zucchini and pumpkins. A trap can be made from any bright yellow bowl or pan that will hold water. The moth is attracted to the yellow color and drowned in the water.  The moths look more like 1/2 inch long orange and black wasps with tiny black dots on their backs and they buzz when they fly. 

You can also try minimizing the impact of the borers by planting a fall crop. Plant the squash seed in July so by the time the plants emerge the moths are gone.

Cook the Suckers: Quick cleanup of infested vines will help to significantly reduce your garden’s squash vine population over a 2 to 3-year period. When the largest part of the harvest of early plantings is over or a plant has died from borer damage, quickly pull the vines and put them in a large black plastic bag for disposal or leave them in the direct sun for a few days and the borers will be toast.

Attract Beneficial Predators to Your Yard: Flycatchers, barn swallows, downy wood peckers, sparrows, blackbirds, grackles and phoebes are some of the common birds that relish squash vine borers and the mother moths.  Moles and toads munch on the cocoons that over-winter in the soil and also go after the borers as they hatch. Wasp parasites will kill the larvae as they emerge and lacewings, spiders and ants eat the eggs.

see all questions...

Do you have a gardening question? Ask Nancy