Squash bugs a problem around area

Kelly Allsup University of Illinois Horticulture Educator
Squash bugs and nymphs.

Squash bugs (Anasa tristis) are eating up squash, melons and pumpkins all over the area. The pumpkins in the organic vegetable garden at Holton Homes in Bloomington have several life stages of the garden pest represented, states Kelly Allsup, University of Illinois Extension Horticulture Educator. Adults and the younger nymphs are sucking the sap from the plants and feeding on the fruits causing moderate to severe plant damage.

The feeding damage causes spots, yellowing and browning of leaves and fruits. Ultimately, the runners or side shoots of the plant can be destroyed.

Adult squash bugs are reminiscent of stink bugs but only emit an odor when crushed. Your plant debris and leaf litter left in the yard provides shelter for overwintering squash bug adults. Starting in the spring months, they begin to lay orange colored eggs on the under sides of your squash leaves and stems in a very precise pattern. Spider looking nymphs will begin to hatch in 1-2 weeks. They have the unusual habit of staying clumped together when first hatched before they disperse.

A squash bug infestation can be detrimental and a large population can kill your entire crop. University of Illinois Extension has several cultural recommendations to reduce the devastation of this garden pest. Remove areas for adult squash bugs to over-winter by cleaning up garden debris, leaf piles and wooden boards and logs. Crop-rotation or skipping a growing season can be helpful. Crop rotation is the method of growing your squash or cucurbit plants in a different location of the garden than last year. It is important to inspect plants for early detection. Lay down wooden boards to lure adults away from plants. Hand-pick eggs, nymphs and adults at first inspection. It is difficult to kill adult squash bugs with pesticides. However, a treatment of horticulture soap, oil or neem oil will reduce the number of eggs and nymphs of squash bugs without unfavorable effects to beneficial insects and pollinators. Spraying will be more effective if good plant coverage of all leaf surfaces and stems is achieved. It is suggested for a gardener not to use a harsher chemical because of the effect these products may have on honey bees pollinating your crops. Treat at dusk to avoid contact with bees.

There is also a beneficial insect called tachinid fly (Trichopoda pennipes) that lays its pale-colored and oval eggs on the underside or sides of large nymph and adult squash bugs. For further information please call Kelly Allsup at 663-8306 or email her at kallsup@illinois.edu.