Updated: Sep 15, 2020
by Marshall Grain Co.
Which do you hate the more: Squash Vine Borers or Squash Bugs? Although they prefer true squashes such as Zucchini, Spaghetti and Yellow squashes, both insects will attack any member of the cucurbita family, including cucumbers, canteloupe, melons, and gourds, if nothing better is around.
It's bad enough when a vegetable is susceptible to just a single horrendously destructive pest, but fighting two of them simultaneously can make squash growing seem like a pointless exercise. But before you give up, read this: There are several organic ways to combat these obnoxious pests and we're going to tell you how.
Watch our video to learn more about controlling squash pests:
First you need to understand what you're up against. Squash Vine Borers require a different strategy than Squash Bugs.
Squash Vine Borers
Squash Vine Borers are the larvae of the Melitta curcurbitae, a harmless moth that lays its eggs on cucurbits. The adult female lay eggs one at a time at the base of susceptible plants.
The bright yellow squash flowers are like a homing beacon to both Squash Borers and Squash Bugs.
When the moth eggs hatch, their larvae bore their way into the stems of the plant and hollow it out as they eat their way through the vines, destroying the vascular tissue that transports water and nutrients to the other parts of the plant. They feed for about four to six weeks and then disappear into the soil where they will remain safely in their cocoon until the next spring.
Once they've bored their way in, Squash Vine Borers are very difficult to get rid of because they are protected inside the stem. Even bacillus thuringiensis is usually ineffective.
How To Stop Them
Your best chance of getting rid of them is to go after the adult moths before they have a chance to lay their eggs. The good news is that the adult moths are easy to trap with our Pest Wizard Squash Vine Borer traps. The non-toxic trap uses no insecticides, making it a perfect solution for the organic gardener. The product attracts the male moth into a sticky trap using a special lure that emits the scent of the female moth. (See our short video on how to put out your trap.)
Watch this video on how to set up the Pest Wizard Squash Vine Borer trap.
Another strategy is to work around them. Squash Vine Borers produce only one set of young per year in mid-spring. Plant a second crop (after they've destroyed your first one!) in early July after the first batch of borers have finished laying their eggs for the year. Your second crop should be safe from vine borers.
Note: Make sure any damaged plants are removed and disposed of off your property to avoid harboring the insect until the next year.
If borers still find a way to attack your squash, you can try to save your plants by finding and killing the larva inside the vine. If your vines are wilting (and you know you don't have Squash Bugs), use a knife to carefully slit the vine, slicing along the stem until you locate the borer. Remove and kill the insect, then mound some moist soil over the undamaged stem. With luck, the stem will develop new roots and you'll have another squash plant.
Another option is to employ beneficial insects such as the Trichogramma wasp or Tachinid fly. Both are parasitic, which means they lay their eggs on the live target insect. Trichogramma wasps are seasonally available from Marshall Grain Co. for you to release in your garden. Keep in mind that beneficial insects take time to work, so to be effective, they must be released early and regularly to keep sufficient populations around throughout the entire breeding season.
You can attract Tachinid flies into the area by growing any type of herb or vegetable that has umbels of flat florets. These would include Queen Anne's Lace, Dill, Fennel, Carrots and Cilantro. Anise Hyssop (Agastache) is also a favorite of Tachinid flies.
Squash Bugs can sometimes confused with Stink Bugs, but Squash Bugs can cause much more damage to your plants. The best advice is, don't wait to find out which is which! Jump on the problem immediately. Again, prevention is the best defense.
Squash Bugs can easily survive for an entire year in your garden. They emerge in mid-spring from their winter hiding places -- they take shelter under garden debris, dead leaves, boards, tree stumps, and even inside buildings. When the weather is warm enough they fly off in search of squash plants (using the plant's yellow blossoms as a sign post).
Once they find a plant, they stay there to lay their eggs. Their clutches of tiny, bronze colored eggs are easy to spot on the underside of the leaves. The adults are also hard to miss, since there are usually hundreds of them congregating together on the foliage of your plants.
When a Squash Bug attacks your plant, it simultaneously injects it with a toxin and sucks the sap out of the plant, which causes it to wilt. You'll see yellow spots that eventually turn brown. The leaves may also have ragged holes.
An Ounce of Prevention
Prevention is the key. Check your plants daily for eggs. Scrape the eggs off the leaf with a butter knife and drop them in soapy water. Another trick is to lay a board on the ground in the evening. Both the adults and the nymphs will congregate under the board. In the early morning before they have a chance to move back onto the plant, crush them. Do this daily until you are certain you've eliminated them all.
Like Squash Vine Borers, Squash Bugs can only produce one generation per year, so you can circumvent them by waiting until July to plant your crop.
Good companion plants for deterring Squash Bugs are Tansy and Nasturtium, so plant some of those along with your Dill, Carrots and Cilantro.
Squash Bug adults and nymphs can also be killed using an organic insecticide such as Triple Action, which is a blend of Neem and Pyrethrin, which is available in our Garden Department. Apply it daily until the bugs have been eliminated.
As with all annual edibles, it's important to practice crop rotation as much as possible to prevent recurrences of diseases and insect infestations. This is especially important since both types of Squash pests over winter in your garden anxiously waiting for you to plant another batch of squash!
By making daily inspections of your vegetables you can spot problems early and get a handle on them before they have a chance to devastate your garden.
Copyright, 2020 Marshall Grain Co., Grapevine, TX