Identifying the Squash Vine Borer and Squash Vine Borer Damage
How to Identify Squash Vine Borers
- Eggs: The eggs are tiny, flat, oval, and brown. The eggs are laid around the bases of squash plants.
- Larvae: If you slit open a stem lengthwise with a fine, sharp knife, you will see the borer larva, which has a fat, white, wrinkled body and brown head; it can grow to about an inch long.
- Moth: The adult squash vine borer is a moth about 1/2 inch long. It has a gray or black body, marked with orange-red on its abdomen, legs, and head. The hind wings are transparent, and the front wings are metallic green.
Identifying Squash Vine Borer Damage
- First, the leaves of the plant will likely start to wilt inexplicably.
- Look for holes at the base of the plant and green or orange-yellow sawdust-like 鈥渇rass,鈥 which is fecal matter (poop!)
- Squash vine borer larvae feed on the material inside the stems of the plants. The stem will start to rot at the site of the feeding first.
How to Prevent Squash Vine Borers
As with most pests, prevention is key.
- Sometimes, the best solution is to start your squash as early as possible. This way, plants will be strong enough to withstand any mid-summer attacks, and you may even be harvesting before squash vine borers become active. If you plant early, you may need to be prepared to cover your plants in case of late frost.
- Do not plant squash in the same area two years in a row. Squash vine borers overwinter in cocoons in the soil. Also, clean up and dispose of ALL plant debris in the fall.
- Dispose of the squash plants as soon as they are finished for the season. In the fall and spring, till the soil to get rid of overwintering pupae.
- Physical barriers can be an effective means of keeping squash vine borers at bay:
- Cover the plants鈥 stems with a barrier, such as strips of nylon stockings or aluminum foil, to prevent egg laying.
- Before flowers appear on the plants, use row covers to keep squash vine borers away. The covers will need to be removed for pollinators, eventually. This will not only give you a head start over pests, but protect your plants from strong heat and frost.
- Adding beneficial insects such as parasitic wasps to your garden prior to the vine borer鈥檚 egg stage can be helpful, as these wasps are the borers鈥 natural enemies.
- If you give up on zucchini, which is susceptible to vine borers, try growing a squash that鈥檚 more resistant. Butternut squash and Cucuzzi (Lagenaria siceraria)鈥攁lso known as the snake gourd鈥攖end to be resistant to squash vine borer attacks.
- Plant extra squash for the pests! This pest is around for only 6 to 8 weeks and can only eat so much (or so we think!), so making sure you have plenty of plants to spare can help you avoid a total loss for the season.
How to Get Rid of Squash Vine Borers
If you鈥檙e already seeing signs of squash vine borers, use these methods to get rid of them or at least minimize their damage to your crops.
- If you catch them VERY early, you can manually remove the squash vine borer. Locate the entry point of the larvae, then slit the stem lengthwise with a fine, sharp knife to remove the larva by hand. One plant can house several larvae. Carefully remove the larvae without doing more damage to the plant. After removal, cover the slit stem section with moist soil above the point of injury to promote the formation of secondary roots. Also, extra rich soil near the vines helps to reroot.
- If you can find the entrance holes and 鈥渟awdust,鈥 try inserting a wire and threading it through the stem for some distance to kill the larvae inside.
- Sprinkle diatomaceous earth around the stalks when the squash vines are small, or the threat of squash vine borers is high (early to mid-summer). Reapply after rain. Also, build up the soil around the vines. Or, sprinkle black pepper around the plants as a defense.
- If possible, catch and destroy the moths at twilight or in the early morning when they are resting on the upper leaves of the plants.
- There are insecticides that work, too, but timing is critical; they are only truly effective when applied at the time when eggs are hatching.
- The bacteria Bacillus thuringiensis v. kurstaki (鈥淏t鈥) is a natural insecticide that can be injected into and applied to the squash stems.
- Insecticides containing the ingredients carbaryl (Sevin) or permethrin will work on squash vine borers, too. Always be sure to read labels and warnings carefully before application of any insecticide.
- Consult your local cooperative extension service for advice on appropriate chemical controls.
- Trap the adult orange moths with yellow sticky traps and yellow-colored bowls of soapy water.
- A trap crop of very early-planted Hubbard squash can be used to alleviate pest pressure on other squash.
- An old folk remedy from The 1963 Old Farmer鈥檚 蜜桃恋人 says that wood ashes were effective against the squash vine borer.
Learn about another main squash and zucchini predator: the squash bug.
Do you have any tips for controlling these pests? Let us know in the comments below!
Catherine Boeckmann
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I had to order by and injector from Amazon and it took a bit. I jammed garlic in oil in the holes and slits until I received the bt. It seemed to stop the damage. Very painful when you have worked so hard to then lose your plant.
Wow, good to know.
Check out this You Tube. Humble Servant Homestead. 鈥淕oing to war with the vine borer.鈥 I鈥檓 going to try his method. It looks like it really works!
Help w/ borer鈥檚
Would be beneficial nematodes work at removing these nasty Critters from soil?
Yes, the use of both beneficial nematodes and of Bt (a beneficial bacteria) has been shown to help prevent squash vine borer. Treat plants and the surrounding soil with these solutions once a week for two to three weeks in early summer, during the time when you see the adult vine borers around.
What does the squash borer larva look like after it ingests the BT? Two plants got totally destroyed by them and I dug out dozens of worms that were nearly an inch long. I've been applying BT all the time now and picking off whatever eggs I can find (100s of eggs and I've seen atleast 5 adults flying around and killed a few). Anyways, lately I've been finding some sticky almost clear gel in places at the base of some of the plants. I've scraped it off with a knife. I'm wondering if this weird gel could be the dying larva and a sign the BT is working?? Or could it be some disease or something? The plants also have powdery mildew.
Will address your powdery mildew situation. Eight to 1 or as little as five to one ratio water to any type of milk. Mix this in a pressure sprayer. Used as a preventative you might not see much powdery mildew. However if you see it start using this once every week to 10 days and you can hold it at bay. You will need to get good at telling the difference between the milk residue and the powdery mildew. This works. There is a natural antifungal reaction when you spray this on the leaves in the hot sun. This is one spray you use In the Heat of the day. The sun with the milk react as a natural fungicide. Covering base of stems, Wood ash around base, Diatomaceous earth around base, and yellow bowls with soapy water countersunk into the soil really help amazingly. Recent scientific research has proven that the borders are attracted to the color yellow. So when the female flowers come out they come.
The weird gel is called frass and is waste from the borer being pushed out of the plant.
I bought bagged dirt from the local plant nursery, free composted sludge from the local water treatment plant. Put the seeds in containers and still got borers...where did they come from?
