Squash bugs (Anasa tristis) and squash vine borers (Melittia cucurbitae) are two of the most destructive pests for squash and pumpkin growers in North America. These native pests have likely been causing damage for thousands of years, following the cultivation of these crops. Understanding their behavior and implementing preventive strategies can help reduce crop loss.
Squash Bugs: Silent but Deadly
Squash bugs are dull gray insects that feed on plant juices, weakening the plants. They also transmit Cucurbit Yellow Vine Disease, which turns affected plants yellow and causes them to die. These bugs lay their eggs on the undersides of leaves, where they hatch into nymphs that spread out and infest the plant.
To manage squash bugs, one effective approach is to use trap crops. Squash bugs prefer certain varieties of squash, like the ‘Blue Hubbard,’ so planting them early in the season can lure the pests away from your main squash crops. The key is to plant trap crops before your vulnerable squash varieties and monitor the trap plants as they attract the bugs.
A practical approach involves planting a few ‘Yellow Crookneck’ squash near your compost pile. While not as attractive to squash bugs as the ‘Blue Hubbard,’ it still draws them in. This also gives you a convenient spot to monitor when squash bugs become active in the garden.
Once squash bugs lay eggs on the trap plants, you can remove and destroy the plants by chopping them up and composting them. This helps reduce the overall pest population. Regular patrols of your garden, including handpicking bugs and rubbing off eggs, can further prevent an infestation.
Fall Trapping for Squash Bugs
In late fall, after the first frost, place a small pumpkin in the area where squash grew. Squash bugs will seek warmth on the pumpkin, making it easy to collect and eliminate them. Soaking them in soapy water is an effective way to kill them. This method can significantly reduce squash bug numbers over the winter.
Squash Vine Borers: A Different Kind of Threat
Squash vine borers lay their eggs at the base of squash plants, where their larvae feed inside the main stems. This feeding weakens the plant and can eventually cause it to break at the base, killing it. The larvae are difficult to eliminate because they feed inside the plant, making handpicking ineffective.
Preventing squash vine borers begins with wrapping the base of each plant with aluminum foil or cheesecloth, which can deter the moths from laying their eggs there. However, if you notice borers after the damage is done, you have a few options to attempt to save the plant. The larvae are usually just an inch above the frass (sawdust-like debris), so you can try to injure or kill them by poking pins through the stem or cutting it open to remove the larvae with tweezers. Cover the wound with soil to protect the plant. Another method is to inject Bacillus thuringiensis into the stem, which can halt borer feeding temporarily.
Choosing Squash Varieties Resistant to Pests
Some squash varieties are naturally less susceptible to these pests. For instance, butternuts and pumpkins like Cucurbita moschata are not preferred by squash bugs and are seldom affected by squash vine borers due to their thinner stems, which make them unsuitable for borers to feed on. One of the best pest-resistant pumpkins is ‘Long Island Cheese,’ a favorite for growers who want to avoid these pests and enjoy a bountiful harvest.
By using these techniques, including trap cropping, pest monitoring, and selecting resistant varieties, you can significantly reduce the damage caused by squash bugs and squash vine borers in your garden, ensuring a healthier, more productive crop.