Squash beetles (Epilachna borealis) are relatives of lady beetles, but while most members of the family Coccinellidae are helpful insects, these beetles are crop pests. You should look for bugs sized slightly larger than a lady beetle with a yellowish-orange color and seven large black spots on each wing cover. Several potential tricks are at your disposal to get rid of squash beetles, but using a combination of approaches may work best.
Surprise the bugs with an attack at high noon. The Purdue University Extension has found this to be the ideal time of day to locate the bugs on your plants. Squash beetles can be controlled through hand-picking. Remove any adults, larvae and eggs. Check the undersides of leaves, as this is where the beetles feed and lay their eggs. Be sure you can identify the egg masses of squash beetles. They are similar to those of lady beetles, but lady beetles are beneficial insects. Look for the bright yellow, bullet-shaped egg masses that differentiate the eggs of squash beetles.
Rotate your garden crops. The North Dakota State University Extension says that squash beetles prefer cucurbits and should not bother plants from other families, such as carrots, tomatoes or beans. Additionally, to draw squash beetles away from a crop you hope to protect, you can plant several crops that the beetles feed upon. For example, if you want to spare your squash plants, add muskmelon, cucumber, pumpkin or watermelon plants to your garden.
Good sanitation practices can prevent squash beetles from surviving the winter in your garden. Remove any crop residue from the garden as soon as the growing season passes. Till any remaining residue into the soil.
A homemade spray featuring hot pepper and garlic components can deter squash beetles from your plants. The North Dakota State University Extension suggests a recipe of liquefied ingredients, including a clove of garlic, a small onion and fresh or powdered habanero, jalapeno or cayenne pepper. Add the ingredients to a quart of water, allow it to steep for an hour, then strain off the solids. Finish the solution with a drop of dish soap. Wear protective gloves for preparation and application.
Wage chemical warfare through the use of insecticides. Products containing endosulfan and carbaryl sprays are effective in controlling squash beetles. You should be aware that you may need to delay harvest from sprayed plants for one to two days depending on the insecticide you use. Usually, you will not find insect populations or damage adequate to require spraying.
- University of Kentucky Entomology; Lady Beetles; Blake Newton; May 25, 2004
- North Dakota State University Extension; Hortiscope -- Questions On: Squash; Ron Smith
- Purdue University Extension; Squash Beetle on Cucurbits; Frankie Lam, et al.; 2008
- Clemson Cooperative Extension; Cucumber, Squash, Melon & Other Cucurbit Insect Pests; Randall P. Griffin, et al.; September 2007
- University of Kentucky Entomology; Ladybugs; Ric Bessin; January 2007