Stink bugs are wider and rounder than squash bugs. In the garden, stink bugs are not a pest of cucurbits and prefer to feed on tomatoes and legumes. Squash bugs feed on garden crops of summer and winter squash as well as pumpkin. Both adults and nymphs can be found near the crown of the plant, underneath leaves or under dirt clods and other protective cover.
When disturbed, they disperse quickly. For overwintering, unmated squash bugs find shelter in the fall under dead leaves, rocks, wood, and other garden debris. Once spring approaches, they fly from their protective habitat to nearby cucurbits where they feed, mate , and lay eggs.
Eggs hatch in 5 to 10 days, and this second generation of squash bugs overwinters and produces eggs the following spring. Injury is limited to squash, pumpkin, melon, and other plants in the cucurbit family. Adults and nymphs cause damage by sucking plant juices. Leaves lose nutrients and water and become speckled, later turning yellow to brown.
Under heavy feeding, plants begin to wilt , and the point of attack becomes black and brittle. Small plants can be killed completely, while larger cucurbits begin to lose runners. The wilting resembles bacterial wilt, which is a disease spread by another pest of squash, the cucumber beetle. The wilting caused by squash bugs is not a true disease.
Squash bugs may feed on developing fruits, causing scarring and death of young fruit. In spring, search for squash bugs hidden under debris, near buildings and in perennial plants in the garden. In some adults, gold and brown spots alternate along the edge of the abdomen. Their shield-like shape often gets them mistaken for broader stinkbugs, but squash bugs only damage cucurbits.
Stinkbugs are much less particular. Adult squash bugs typically live up to days, and two generations per season are common. Adults lay very distinctive shiny, copper-colored eggs beginning in late spring or early summer, which soon hatch into hungry offspring known as nymphs.
During the 33 days before full adulthood, nymphs molt repeatedly and pass through five stages called instars. Both nymphs and adult squash bugs feed on cucurbit plants, often congregating in very large numbers. When feeding, mature and immature squash bugs pierce the tissue of cucurbits and suck out the plant juices.
They feed on leaves, vines and even fruit. The damage done by squash bugs is particularly destructive; they pierce plants in multiple sites, causing vines and leaves to collapse as they suck the sap. In addition, squash bug saliva released during feeding carries bacteria toxic to cucurbit plants.
Nymphs start out a pale green color and molt in later stages into larger gray nymphs, and finally change into gray-to-black adult squash bugs. Controlling squash bugs in the home garden starts now, in the fall. Removal of debris in and around the garden, including old plants, will reduce the areas where the adult bugs can hide and survive the winter. Once spring arrives managing this pest is more direct.
Check for eggs on undersides of leaves and remove them before they can hatch and cause damage. The smart gardener will continue to scout their pumpkins and squash plants from spring to mid-summer, searching for nymphs and eliminating them as they are found. Boards placed in the garden near the plants, provides squash bugs a place to hide on a cool night. These boards can be checked in the morning for squash bugs, which can then be easily eliminated.
If you have had squash bugs before, your chances of getting them again are high — unless you do something to intervene. Remove the old vines and leaf litter from your garden where adult squash bugs overwinter.
This will greatly reduce the population that emerges at the beginning of the growing season. In a heavily mulched garden, squash bugs will have many places to hide. Plastic mulch thin sheets of plastic perforated for water to pass through is an appropriate mulch for squash because it will provide the weed suppression of organic mulch while not providing habitat for pests. For instance, where squash were grown the year before, plant nightshades like tomatoes and peppers , root crops like radishes and carrots or salad greens, because these edibles are not susceptible to squash bugs and cucurbit diseases.
Certain squash varieties are far less likely to be attacked by squash bugs than others. These include acorn squash, spaghetti squash, butternut squash and zucchini. Certain squash varieties like zucchini are less likely to be attacked by squash bugs than other varieties. Nasturtium , a vining plant with edible leaves and flowers, is said to repel squash bugs. Interplanting nasturtium with your cucurbits as a companion plant may keep squash bugs away.
Floating row cover installed over squash seedlings will deny squash bugs the opportunity to lay their eggs — at least in your garden. This thin barrier lets light and water through but not squash bugs and other squash pests, such as squash vine borer and squash beetles. However, row cover also excludes pollinating insects, so it should be removed when the plants begin to flower.
You can continue to use row cover until the threat of squash bugs has completely passed if you hand-pollinate. First, identify a female flower to pollinate. You can recognize female flowers by the small embryonic fruit between the flower and the plant stem.
Next, identify a male flower — there will be nothing between the flower and the stem — and peel back the petals to reveal the pollen-covered anther. Brush the anther around the stigma of the female flower, and then close the flower with a lightweight clip clothespin to allow the pollination process to complete.
My preferred method is to cover the pollinated flower in a nylon mesh netting bag.
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