Squash Bug

Squash bugs suck the sap from squash and pumpkin plants.

Squash bug adults are dark-grayish brown in color and are about 5/8 inch long. Nymphs are pale green in color and become brown as they grow. Eggs are bronze-colored and are laid in clusters of about 20 on the undersides of leaves,


Damage Caused by Squash Bugs

The squash bug is a common pest in pumpkins and squash in Illinois.

  • Both the adults and nymphs use their straw-like mouthparts (piercing-sucking) to suck the sap out of plants.
  • Their feeding causes yellow spots to form on leaves.
  • These leaves will eventually turn brown and die.
  • In addition to damaging the leaves, their feeding can also disrupt the flow of water and nutrients to the leaves. Because of this, leaves will often wilt.

Younger plants are much more vulnerable to feeding damage and can be killed if feeding is too extensive. While larger, vigorous plants can tolerate more feeding damage, runners can still be damaged or killed.

Squash bugs may occasionally feed on the fruits of the plants, causing sunken dead areas (which can allow rot organisms to get in).


Life Cycle of the Squash Bug

Adult squash bugs will overwinter in protected areas (under plant debris, around buildings) and emerge in the spring. When they emerge, they will seek out cucurbit plants to feed on as well as mate. Females will lay clusters of eggs on the undersides of leaves, commonly where two veins meet to form a V, or on stems starting in June. The eggs will hatch about one to two weeks later, typically from mid-June to mid-July. It takes them approximately five weeks for them to go from an egg to an adult.


Management of Squash Bugs

Since the bugs overwinter on plant debris, good sanitation in the garden is important.

  • Make sure to remove plant debris in the fall, especially if you had issues with them during the growing season.
  • The bugs may also hide out in mulch.
  • If populations get high, it may be a good idea to remove it to reduce the number of hiding spots they have.
  • Make sure you are growing healthy, vigorous plants by providing adequate water and fertility, healthy plants can tolerate more damage than sickly ones.

Both adults and nymphs can be hand-picked from plants. They can be knocked off plants or dropped into a bucket of soapy water. It's important to note that both the adults and nymphs are 'shy' and will quickly run for cover when they are disturbed. Egg masses can be crushed or removed from the plant and destroyed.

  • Placing boards, pieces of newspaper, or cardboard can be placed in the garden to trap the bugs. The bugs will congregate under them at night. Then, come morning, they can be removed.
  • Row covers can be used on plants until they bloom. Once plants begin to bloom, the cover will need to be removed so flowers can be pollinated.
  • Insecticides can also be used to manage populations of squash bugs. Chemicals are most effective on young nymphs, the older and larger they get the less effective they are. If plants are blooming while you are using insecticides make sure to apply them when bee activity will be at a minimum, usually early in the morning or in the evening. As always make sure to read and follow all label directions.

Contact your county Extension office for current pesticide controls.