One of the most ubiquitous vegetables for the summer garden is squash. Zucchini, yellow crookneck, even the less common patty pan squashes are easy to grow and prolific. They’re easy, that is, until the critters that also love squash show up in your garden.
The dreaded squash bug is one of the worst offenders. At about an inch or more long, the dark brownish-gray bug moves around quickly on the plant and reproduces prolifically. The eggs are a beautiful bronze color, laid in clusters often on the underside of a leaf next to a leaf vein. The nymphs (the child and teenage version of the adults) are grayish-white with dark legs, heads and antennae.
As a member of the true bug family, squash bugs have needle-like mouthparts, which they insert into squash leaves to suck out plant juices. While feeding, squash bugs inject toxins into the plant, causing the vines to turn black and dry out. Squash bugs will also feed on developing fruit.
Squash bugs are challenging to manage. Begin by keeping plants well-watered and fertilized properly so they can better withstand squash bug feeding. Scout early and often, and follow the verb form of the plant name as a plan of action: squash! Look for the neatly arranged bronze eggs and remove. The newly hatched nymphs tend to aggregate initially: with any luck, you can catch them all together and easily squash them all. Otherwise you’re chasing down the nymphs and adults alike.
One practice is to place a board on the ground amid the squash plants. The bugs will often gather under the boards at night and early in the morning, flip over the board and destroy them. If you’re squeamish about squashing, take a mason jar or other container with you to the garden, full of warm soapy water. You can knock the bugs into the jar; the soap keeps them from escaping as it breaks the surface tension of the water and they quickly sink. Keeping the garden clean of squash plant debris, especially at the end of the season, can also reduce the pest numbers the following year.
Another particularly noxious pest of squash is the Squash Vine Borer. SVB is the larval form of a type of insect called a clearwing moth. They actually look more like a wasp than a moth. The adult is quite striking, with an orange abdomen with black dots, black wings and antennae. At least, that’s what the picture shows: I’ve never seen one in person, though I’ve had run-ins with plenty of its progeny.
The larvae are creamy-white, with black heads, and look like a worm-shaped Michelin Man. With this pest in particular, it is usually after we see damage — in the form of wilting vines — that we realize we have a problem. Adult moths emerge from cocoons in the soil in early summer and lay eggs singly on the leaf stalks and vines of squash plants. The eggs hatch in seven to 10 days, when the tiny larvae tunnel into the stem of the plant.
From this point, chemical control of the pest is not effective, as the larvae are protected inside the vine. The larva then eats its way up the stem or leaf petiole. A saw-dust like frass (larval waste) is a sign of pest presence, even before the plant begins to wilt.
Homeowners with the time and inclination can have some luck getting rid of the pest by chasing the worm down in the stem with a knife or other sharp object. From personal experience I can tell you a stiff privet stem, stripped of leaves, works well for this purpose. Not only is it possible to save the squash plant in many cases, there is undeniable satisfaction in skewering the critter that is bent on destroying the squash vines.
If the larvae can be removed without too much damage to the stem, cover the damaged stem area with soil and often the vine can continue producing. Likewise, by encouraging the vine to root at multiple nodes with soil layering, if one part of the vine is affected, the remainder can continue growing from the newly developed roots.
Squash bug and Squash Vine Borer rank as the worst of the pests of squashes, though there are others, such as pickleworm and Squash Beetle. Squash bugs will also attack other cucurbit crops such as melons and cucumbers. The key to managing these pests is understanding their life cycle coupled with early and frequent scouting to prevent pest populations from getting out of hand.
It is also a good idea to have a few new squash plants started that can replace your first planting, when pests and maybe some diseases, such as powdery mildew, finally overtake them. Squash can continue to produce up to first frost, on healthy plants.
For more information on successful vegetable gardening, contact Richmond County Cooperative Extension, 123 Caroline St., Rockingham, at 910-997-8255.
Paige Burns is assistant horticulture agent at the N.C. Cooperative Extension’s Richmond County Center.