It’s August and the garden is doing well…or so you thought. You may have noticed damage to some of the vegetables in your garden. Here’s some information on two common vegetable garden pests for this time of year and tips to control them:
Squash bugs attack plants in the cucurbit family: melons, squash, pumpkins and cucumbers. They damage plants with their sucking mouthparts, feeding on leaves and stems. The damage starts as speckling on leaves and stems, but a large infestation can cause vines and leaves to wilt and then die. Squash bugs hide on the undersides of the leaves. Their gray to brown coloring also helps them blend into the soil. They lay clusters of root beer -colored, barrel-shaped eggs on the undersides of leaves. The eggs hatch in 10 days, and the nymphs turn into adults in four to six weeks. You can have several generations of squash bugs each growing season.
Insecticides are not very effective against squash bugs. It is difficult to apply them on the insects, and applying insecticides during our high summer temperatures can damage your cucurbit plants. Your best bet is to handpick the adults, nymphs and eggs off the plants. This is best done early in the morning, when they are not moving very fast. Scrape the eggs into a cup of soapy water (dish soap works well). At the same time, handpick and drown the adults and nymphs in the soapy water. Dump the soapy water and drowned insects in the trash. To prevent an infestation next year, clean up all debris in the garden at the end of the growing season. Adult squash bugs will overwinter in your garden debris and attack your cucurbit plants next spring if you don’t practice good sanitation. Rotating crops can also help reduce infestations, but remember adult squash bugs have wings, and they can and do migrate in and out of your garden.
Another common vegetable garden pest being reported right now is the cabbage looper, a 1- to 1.5-inch green caterpillar. Loopers move like inchworms, looping their bodies up before moving forward. They are the larval stage of a light brown to silvery moth. Are you noticing ragged holes in the under leaves or in the heads of your some of your cabbage plants? They will also feed on kale, broccoli, cauliflower, beets, lettuce, potatoes, tomatoes, cucumbers and melons. Damage on the outside leaves is not a big problem, since these are usually discarded before the plants are consumed. But, when they attack the cabbage heads, damaging the center of the plant and leaving behind their droppings, many gardeners want control NOW. Because these pests attack plants meant for our table, most gardeners do not want to apply insecticides. Hand picking is a good option. Microbial insecticides are another control option. Bacillus thuringiensis (Bt) kurstaki is a bacterium that produces a toxin that kills many kinds of caterpillars but does not harm beneficial insects.
For additional information on these and other insect pests, go to www.manageNVpests.info and check out the insect and arachnid pests photo gallery.
Melody Hefner is a Water Quality and Pesticide Safety Program Assistant for the University of Nevada Cooperative Extension.