Growing Giants in Illinois

  • Squash bugs like to hide under leaves
  • Adults are the hardest to kill
  • A product with Bifenthrin at 7.9% works well 
  • One bite from a infected sqaush bug can kill your plant
  • Clean up debris so they have less areas to overwinter

The Monsters in your garden

Squash Bugs

Squash bug

The squash bug may be enemy number one when it comes to cucurbit crops. Cucumber and melons are the least favored and are rarely eaten, hard winter squash and pumpkins would be the favorite of the squash bugs followed by summer squash. Adults and nymphs both feed on crops and they can be hard to control with the nymphs being the easiest to kill . Plants should be searched for eggs at least once per week, egg laying usually begins in June. Squash bugs  can be easily confused with a Stink bug (Euschistus conspersus) the stink bug does not eat cucurbits and prefers legumes and tomatoes. Both of these true Bugs give off a foul odor  when crushed.

Life cycle

Having a lifespan of 75 to 130 days hard adults overwinter around the plants from the previous year under debris, around the garden, and in woodlands, removing mulch can reduce their numbers . Young nymphs will die in the fall when temperatures drop, usually dying at first frost.   Adults emerge once temperatures start to warm in late spring, they may feed on germinating plants completely destroying them.As feeding occurs during late spring mating will begin sometime in June and can last through summer with one generation in northern climates and 2 to 3 in southern areas.

Females lay several groups of eggs consisting of about  20 Eggs laid neatly under the leaf where  the plants veins form a V. Being slightly oval in shape , shiny with a color range of bronze , red, copper  and yellowish-brown and approx 1/16 “ long. Hatching in 7 to 9days they  look similar to tiny spiders and will go through 4 more nymphal instars getting darker each time almost always staying in a group , they seem to favor company, living in loose organized  communities.


Adults, as well as nymphs, use their piercing mouthparts to suck sap from the plant while also excreting toxic saliva disrupting  the flow of water and nutrients. Adults and older nymphs feed on the whole plant while  the young nymphs feed near where they hatched While the leaves take the most damage the fruits can also be  eaten  making them to unsightly for market. Attacked leaves can quickly wilt turn brown and die if feeding is heavy, entire vines can die off starting where the damage occurs and traveling down to the vine tip. Wilting of vines can be misdiagnosed as having Bacterial wilt when actually it could be Yellow Vine Disease (Yellow Vine Decline) squash bugs can vector this bacteria, (Serratia marcescens) which causes leaves to yellow and  wilt, then it can travel through the entire plant killing it withen days.

Follow directions and your state and local laws when using insecticides, you may want to  contact your local cooperative extension office to obtain a private applicator’s pesticide license they will teach you the proper application of chemicals and how to handle them safely.

Hand picking insects and manually removing or crushing the eggs can be an effective way of  control .Squash bugs enjoy collecting around the base of plants  ,keeping this area free of debris reduces numbers.Diatomaceous earth and insecticides can be used in this area too. Imidacloprid is a systemic insecticide that will travel through the entire plant, it kills after the insect has eaten but can damage bee populations. Bifenthrin will kill the hard to control adults and nymphs and Pyrethrin and Lambda-cyhalothrin helps to control them also . Bifenthrin at 7.9% seems to be the most widely used at 1/2 to 1 oz per gallon every 7 days.

Quickly disposing of plant materials at the end of season can help reduce next year’s population, by removing their food source they won’t have enough energy to survive the winter.

newly hatched Squash bugs

squash bugs

Stink Bugs