University of Illinois Extension

Bugs in the Garden

Late summer and fall can mean large populations of biological insects flocking to your garden from nearby fields, said Candice Miller, U of I Extension horticulturist.

"Although some of these insects may be considered a nuisance, they really are a welcome site to your garden," explained Miller. "A lady beetle for instance may eat its weight in aphids every day as a larva and consume as many as 50 aphids per day as an adult; a welcome predator to save our aphid infested garden plants."

Lady beetles are oval, convex, and about one-fourth inch long ranging in color from tan to orange to red, usually with several black spots on the wing covers.

"What makes lady beetles a nuisance to some is that as fall approaches, the adult beetles leave their summer feeding sites to look for protected places to spend the winter," she said. "Unfortunately this means a flush of lady beetles trying to enter our homes around September and October."

Lady beetles work their way into buildings through cracks and crevices, but a home or building shaded from afternoon sun is less likely to attract beetles. Studies have shown that lady beetles are attracted to illuminated surfaces so they tend to congregate on the sunnier, southwest sides of buildings illuminated by afternoon sun.

"Avoid this invasion by caulking or sealing cracks and crevices in your home," she said. "If beetles do enter your home, simply physically remove by sweeping or vacuuming and release outdoors in a garden away from your house. Do not kill the beetles because once crushed, the beetles will emit a foul odor and leave a stain."

Another great beneficial insect to see flocking to your garden is the minute pirate bug. The minute pirate bug is about one-eighth inch long, oval to triangular in shape, flattened and black with whitish markings on the back. Using their piercing sucking mouthparts, they take body fluids from insect eggs, spider mites and small insects such as aphids, thrips and leafhoppers. These insects can consume as many as 30 spider mites per day, a great benefit to the garden.

"The unfortunate nuisance of the minute pirate bug though, is the surprisingly painful bite that can be inflicted by such a small insect," she said. "According to researchers, the reason they bite is still a bit of a mystery. However, it is known that they bite when it is warm out and usually bite people who are perspiring slightly. They do not take blood or inject any saliva, so in most cases, their bite is not particularly serious to most people.

"Although these two pests may be a slight nuisance, the benefit they bring to our garden really outweighs the slight nuisance in my opinion."