As summer approaches, and warm weather crops are coming in, we are all looking forward to a harvest of beautiful zucchini, sweet butternut squash, and bright orange pumpkins! But there is an enemy of all gardeners who grow summer squash and winter squash varieties alike. It can kill a completely healthy plant and stop your garden fun right in its tracks.
What is it? The dreaded squash vine borer! Let’s take up arms against our common enemy with organic pest control methods that will help you keep your squash plants bug free!
Why I Choose Organic Pest Control
I love using natural and organic pest control methods in my garden. Not only can they be highly effective, but they are safer and healthier for people and the environment.
That is why we carry a line of organic pesticides and share blog posts that explain natural pest control methods for controling spider mites, reducing fungus gnats, keeping pest animals out of the garden, and more.
What Is a Squash Vine Borer
The squash vine borer is a serious pest that targets squash and sometimes other cucurbit plants. The adult melittia cucurbitae (squash vine beetle) is a moth that is black with a reddish-orange abdomen.
They fly during the day and are often mistaken for wasps. You may have seen them flying around your summer squash and winter squash plants.
The larvae, on the other hand, are a creamy white grub with brown heads that grow to about an inch long. They can be found in the stem of a squash plant once the squash has been affected.
Life Cycle
Adult moths lay eggs on the base of squash plant stems. Those eggs hatch in one or two weeks, and the resulting larvae bore into the stems of squash plants (and sometimes even the fruit) and eat vines from the inside out!
The larvae feed on the plant for four to six weeks. Then, the mature larvae leave the plant and burrow into the soil, where they pupate overwinter. In June or July the following year, the adult moth emerges and lays eggs. And so the cycle continues.
Signs of Squash Vine Borer Damage
If you monitor your squash plants regularly, you may notice adult vine borers near your plants or tiny, flat, oval-shaped brown eggs usually attached to the base of the stems or the undersides of leaves. Those easily go unnoticed, so the first thing most people see when squash vine borers are attacking their plants is wilting.
If you notice your squash are looking wilted, examine your plants closely for holes near the base of the stems. The holes will be filled with a sawdust-like green to orange “frass”, which is fecal matter from the vine borer.
Look for these common signs of squash vine borer damage:
Wilting - A healthy plant turns to a wilted plant in a matter of a few days, and won't recover after watering
Holes - There are small holes where the larvae have tunneled in
Stem Rot - The squash plant stems begin to get mushy and rotten
Stunted - The plant is significantly stunted plant and eventually dies
Squash vine borer damage is incurable about 90% of the time once they’ve invaded the stem of the plant. On rare occasions, the plant will survive, but almost always they will kill the plant. Pro-Tip: If you want to try saving the plant, remove and destroy wilted or dead vines immediately. Then use the pest control methods listed below.
Methods to Prevent & Manage The Squash Vine Borer
It doesn’t matter if you’re growing a zucchini plant or growing a pumpkin plant, no one wants to see their crop devastated right before their eyes. Use these natural methods early and often to keep squash vine borers away for good:
Remove Eggs - The adult moth does no damage to the plant at all, so the focus should be on preventing the larvae. Removing eggs is effective and will stop the life cycle of the moth. Check each plant once weekly in the months of July and August. Eggs will be deposited on the undersides of the leaves or the base of stems. The downside of this method is that removing the eggs is labor-intensive and, even with frequent, diligent checking, often some are missed.
Intercropping - As I’ve said before, biodiversity is great organic pest control. Plant fragrant plants around your squash to mask the scent, such as onions, mint, basil, parsley, and marigolds. Intercropping is an effective way to keep pests aways from your plants!
Oil Scent Masking - This method is HIGHLY effective when used correctly. Take a very strong essential oil, like quality peppermint oil, and dab 3 Q-tips into the oil. Poke the Q-tips in the ground with the scented end facing up in a triangle pattern around the base of the plant, about 2 inches out. You can also use cotton balls if you don’t have Q-tips. Pro-Tip: Peppermint oil has been proven to deter squash vine borers, plus ants, spider mites, and even squirrels in the garden!
Thuricide - The active ingredient in Bonide Thuricide BT Concentrate is Bacillus thuringiensis, which is a naturally occurring soil-born bacteria that is used for natural insect control of moths, moth larvae, and leaf eating worms. Thuricide is considered non-toxic and won’t harm harm beneficial insects, animals, or people.
Some other methods of prevention and management include trapping adult moths, using physical barriers (like row covers) to protect plants, and sprinkling diatomaceous earth around and on the plant’s base. These are helpful in your defense, but the four pest control methods listed above I have found most effective against the squash vine borer.
Pro-Tip: Keep your squash plants healthy and stress-free! The only way adult moths can find a squash plant is by smell. When a plant is distressed, it releases a chemical scent that attracts the moths. The stress could be from pest damage, lack of water, or even lack of nutrients. Not every plant can be 100% healthy, and it only takes one plant to spoil it for the rest.
