Squash Bug


Squash Bug Life Stages Squash Bug Life Stages

Squash Bug Nymphs Feeding on a Pumpkin Squash Bug Nymphs Feeding on a Pumpkin

Squash Bug Nymphs on a SquashSquash Bug Nymphs on a Squash

Feeding Damage on PumpkinsFeeding Damage on Pumpkins


  • Cucumber
  • Melons
  • Winter Squash
  • Summer Squash


Squash bugs are the primary pest of cucurbit crops, and can kill plants. They feed with a piercing-sucking mouthpart, removing large amounts of plant sap. In Utah, they do not vector plant diseases.


Adults are 5/8-inch long with wings folded over a flat back. They emit a foul odor when disturbed and some people call them “stink bugs”; however, true stink bugs are in a different insect family. There are five nymph squash bug stages (immatures), that range in color from reddish to green-gray. Eggs are shiny bronze and are found on the underside of leaves.


Egg | Nymph | Adult
Squash bugs spend the winter as adults in protected sites under plant debris, compost piles, around building foundations, etc. They emerge in spring, typically during April in southern Utah and during May in northern Utah. They fly to host plants to feed, mate, and lay eggs. Each female lays up to 250 clusters of 4-40 eggs on the undersides of leaves. The eggs hatch into nymphs that take 4 to 6 weeks to mature to adults. The summer generation of adults appears in late July in northern Utah (3 to 4 weeks earlier in southern Utah), and feed on cucurbit hosts while they build up fat reserves to survive the winter.


  • Scars and desiccated, sunken areas on fruits
  • Wilting foliage during the day (due to lack of plant sap) and recovery at night
  • Complete plant decline


One of the most important strategies is reducing the squash bug population through careful monitoring and removal of eggs.
  • In the spring, look for adult squash bugs  in plant debris and perennial plants.
  • Monitor for eggs regularly on the underside of leaves.


  • Remove or kill eggs using duct tape to remove eggs, smearing eggs with oil, or cutting out the section of the leaf with eggs.
  • Physically remove adults and nymphs by hand and drown them in soapy water.
  • Pull out plants right after harvest to remove overwintering sites for adults.
  • Rotate with non-cucurbit crops to minimize the population of overwintering adults.
  • Plant cucurbit varieties with resistance to squash bugs, such as butternut and royal acorn squash.


Adult squash bugs are tolerant of insecticides, so if you choose to spray, begin shortly after egg hatch to target nymphs instead. To be effective, insecticide sprays must penetrate the plant canopy and thoroughly cover the top and underside of leaves, fruits, and vines. Don’t spray during the day when plants are blossoming, to avoid harming pollinators.
Insecticides for commercial production.
Insecticides for home gardening.

Precautionary Statement: Utah State University and its employees are not responsible for the use, misuse, or damage caused by application or misapplication of products or information mentioned in this document. All pesticides are labeled with ingredients, instructions, and risks, and not all are registered for edible crops. “Restricted use” pesticides may only be applied by a licensed applicator. The pesticide applicator is legally responsible for proper use. USU makes no endorsement of the products listed in this publication.