Friday, May 17, 2024

Squash Vine Borers – The Best Hide and Seek Players in Your Garden

Squash Vine Borer Larva
Squash vine borers have figured out how to drive gardeners and growers crazy. Their sneaky and hidden ways can devastate all your squash plants before you realize it’s too late. Even when you realize you have a problem, they are already inside the stems of your squash plants, and there is little you can do to save your plants.

However, there is hope in preventing them from destroying this year’s bounty of squash. This article offers proven, eco-friendly methods to prevent these pests from ruining your squash crops.

We’ll learn more about:
  • The life cycle of squash vine borers
  • Effective strategies to keep them out of our squash
  • Early detection techniques for better management

Let’s begin by exploring the life cycle of squash vine borers, which is key to effective management.

Squash Vine Borer: Lifecycle and Impact

Identification and Lifecycle

Adult Squash Vine Borer
Adults are colorful moths that emerge from the soil in the end of spring. The moths have metallic green forewings and clear hindwings that are often folded and tucked away when they land.

Females will lay their eggs in early spring at the base of squash plants. Approximately one week later, these eggs hatch, and the larvae immediately burrow into the plant stems. Inside, they begin consuming the core, disrupting water flow and causing the leaves to wilt. Severe damage can result in the death of the plant.

After feeding for 4-6 weeks, the squash vine borer drills a hole out of the stem, and will pupate in the soil. It stays in its cozy cocoon until the next spring or summer. Most squash vine borers will only have one generation each year. However, populations in the south can often have two.

Damage and Symptoms

Squash Vine Borer Damage

It’s often hard to tell that you have a problem, until the damage is done. The biggest sign is that your squash plants are all-of-sudden wilting. This will begin happening in full sun, and if the problem isn’t corrected, you should see the wilting in the mornings too.

Look for bore holes at the base of plants, along with sawdust-like frass (or insect feces). The base of the plant may start to rot or feel soft. If you notice these symptoms, then you need to start treatment options and prevention for next year’s squash.

Eco-friendly Methods to Control Squash Vine Borer Populations

It can seem daunting to prevent or kill squash vine borers. However, with a few proactive strategies, you can keep your squash in full production for longer.

Monitoring and Trapping

Before you start planning out your treatment strategies against squash vine borers, it’s important you know you have a problem first. Begin by setting out pheromone traps for adult moths. These lures can also be helpful in reducing the number of eggs laid on your squash plants. It’s also been shown that using pheromone traps can reduce the amount of pesticides used to control squash vine borers.


Sometimes you can’t catch all the female moths ready to lay eggs. However, you can prevent them from getting to your squash plants. Row covers will prevent females from getting access to the base of your plants and prevent them from laying eggs.

You can also wrap the base of each individual plant with aluminum foil or panty house to prevent larvae from burrowing into the stems.

Organic Insecticides

Organic treatments such as spinosad, azadirachtin, and Beauveria bassiana have been used effectively to control squash vine borer populations. These organic insecticides significantly reduce infestation levels, providing a robust defense against squash vine borers while adhering to organic agricultural standards.

However, these are only effective against adult moths and won’t affect larvae once they are inside the squash plant.

Bacillus thuringiensis

Bacillus thuringiensis is a very effective treatment against moth and butterfly pests. You can even use it against larvae that have already dug into a stem. You will need to inject the Bt product into the stem or applied as a foliar spray. This can be an effective way to treat squash vine borers once they are already growing in your plants.  


Another interesting tactic is to target the pupating moths that are in the ground. To do that, you can use a beneficial nematode product. The nematodes will seek out any pupae in the ground and infect them. This is a great way to prevent any new outbreaks of squash vine borer.


Squash vine borers can be tricky to control if you don’t get the timing of their emergence and egg-laying just right. Even if you aren’t 100% effective in stopping egg laying, there are still a few options to keep your squash harvest abundant this year. - Grant @ ARBICO Organics

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