Saturday, November 26, 2022

To Squash a Pest: Squash Vine Borers and the Endless War on Squash

The Squash Vine Borer is native to the eastern coast and is a common pest among squash crops. (Courtesy of Wikipedia)

REGIONAL — They’re a troublesome pest for those trying to grow a bountiful squash crop. Squash Vine Borers are wasp-like moths that can decimate a squash plant.  They have dark metallic forewings and an orange abdomen with black dots and are often mistaken for wasps. 

According to Dr. Lorena Lopez with Virginia Tech’s Department of Entomology, the insects are hard to detect because of how they lay their eggs. 

“They lay single eggs at the base of the stem, so it’s hard to see,” she said in a phone interview.

The adults only live for four to five days, but they can lay up to 200 eggs in that time, Lopez added. 

Once the eggs hatch, they’ll burrow into the plant tissue and live there for four to six weeks before dropping to the ground. It takes the larvae eight weeks in Virginia to become adults.

Plants that have been affected by the insects will start to droop, but instead of plants in a row drooping, it will appear in patches, which suggests an insect problem rather than a watering issue. 

And there is no good way to save a plant that has already been infected. Lopez said the best thing a grower can do is destroy the plant to protect the rest of the crop. 

So how bad are the squash vine borers this growing season? 

Lopez works at Virginia Tech’s Eastern Shore Agricultural Research and Extension Center where they have several experiments involving squash vine borers. This year’s squash crops had to be planted a few weeks late due to a drought in the spring, but Lopez said so far, 30% of their plants have been affected by the insect. 

“They’ve been all over the squash, so it has hit us very hard,” Lopez said. 

There are a few options for those trying to protect their plants. 

Choosing when to plant has a large impact on when the insects attack the plants. The squash vine borers are active from late spring to August. Lopez suggests planting earlier in the spring if possible. Waiting to plant later in the summer is preferable for fall squash. 

Tilling the soil before planting can also help kill off the larvae that fell to the ground.

While there are some pesticides that will take care of the squash vine borers, they’re not preferable because they’re also toxic to bees, which are needed to pollinate the squash once it flowers.

Before the plant flowers and requires pollination, row covers can protect the plants for the four to five weeks before flowering.

For more information on the Virginia Tech’s Eastern Shore Agricultural Research and Extension Center, click here.

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