Squash Bug

The squash bug is one of the most common and troublesome pests attacking squash and pumpkin plants. Feeding, via piercing/sucking mouthparts, occurs primarily on the plant foliage. However, late in the season, squash bugs may also feed on fruit. The

associated damage symptoms include wilting of leaves and ultimately results in leaves that appear black or dried out.

Squash bugs are secretive in habit. Both adults and nymphs are found clustered near the plant crown, beneath damaged leaves, under clods or in any protective groundcover.They all scamper quickly for cover when disturbed.

The squash bug can be misidentified as a stinkbug. Both insects look similar and emit a distinct odor when crushed; however, the stinkbug is not a pest of cucurbits and is more commonly associated with tomatoes or various legumes such as soybeans and peas.

Description

Adult squash bugs are about 1/2 inch long and are winged. They are usually gray to black with the edges of the abdomen having orange and brown stripes. Nymphs are 3/16 to 1/2 inch in length. Young nymphs have a red head and legs with a green abdomen,however, as the nymphs age the red color will turn to black.

Life Cycle

Unmated adults overwinter and find shelter during the early fall under plant debris, around buildings, under rocks, etc; nymphs will die off as temperatures begin to drop. They emerge in spring and will fly to cucurbits when vines start to grow. Eggs are laid from spring to midsummer under the leaves in a characteristic V shape pattern following the leaf veins. It will take 1-2 weeks to hatch. All life stages occur throughout the summer months.

Damage

Both nymphs and adults suck sap from the leaves and stems, apparently also  injecting a toxic substance into the plant, causing a wilting. After wilting, vines and leaves turn black and crisp and become brittle. Small plants are killed entirely while larger plants may  have several runners affected. Wilting can look similar to bacterial wilt, however, bacterial wilt is much more detrimental. Once the squash bug population is reduced, wilted plants should recover. By contrast, plants infected with bacterial wilt will continue to decline and will eventually die. Therefore, it is important to determine which wilt is occurring; the correct identification of the insect pests present in the field is an essential first step. Squash bugs will also feed directly on fruit.

Management

Early detection of adult squash bugs is very important as they are difficult to kill and can cause considerable damage.

Prevention: Using resistant varieties such as Butternut, Royal Acorn, or Sweet Cheese and maintaining a healthy plant through proper fertilization and watering are also important to limiting squash bug damage. If only a few vinesare involved, collect and destroy the bugs and crush their egg masses. Some gardeners place pieces of board or shingles on the ground near the plants to concentrate the number of individuals in an accessible area. Plant remnants may be composted or burned at the end of the year. It is a good idea to select varieties of squash and pumpkin that are resistant to the squash bug. Since there is only one generation per year, damage can be greatly reduced by keeping vines covered until blossoming begins. Remove the cover for pollination purposes.

Insecticides: If prevention methods are inadequate, chemical insecticides registered for garden use [e.g., carbaryl (Sevin), methoxychlor, Endosulfan (Thiodan)] can be applied, according to label directions and safety precautions. Repeat applications may be needed.

Adapted from: Ohio State University Extension, 1999; Amber Genetzky, Eric Burkness, and W.D. Hutchison, The University of Minnesota Extension Service, 2004