The Homeowners Column

The Homeowners Column

Good bugs, bad bugs and fun bugs to watch

Photo of Sandra Mason

Sandra Mason
Extension Educator, Horticulture
slmason@illinois.edu

A February landscape scene is usually framed by a window as we look out from the cozy warmth of our homes. However, this year the weather is perfect for wandering around our yards. Recently in my yard tour I saw the leaves of spring flowering bulbs peeking through the mulch. Ladybugs were covering the leaves as an undulating red mass of black polka dots. As I admired my birch trees I noticed the egg masses of tent caterpillars. They form a dark brown or grey turtleneck encircling small twigs. A quick scratch with my thumbnail took care of that future problem. I also noticed some egg cases of my resident praying mantids.

Around my house we see egg cases of both the Chinese praying mantis and the smaller Carolina mantis. The Chinese egg case resembles a mass of brown foam insulation about 2 inches long, often surrounding a plant stem. The smaller Carolina mantids have a 1 1/2 inch long case that looks like a brown zipper stuck to tree limbs, or hard surfaces such as fence boards or houses. I left the mantis egg cases where I found them.

During my wandering I had quickly made some decisions about good bugs, bad bugs and fun bugs to watch. Lady bugs are good bugs. The adults and young larvae have voracious appetites for those bad guys - aphids. (Ok, the multicolored Asian lady beetle has given the other ladies a bad name with their wanderings inside our homes, but for the most part they are good.) Tent caterpillars eat the leaves of fruit trees, birch and many other trees. Mantids are in the fascinatingly fun category.

The young and adult mantids feed on just about any insect they can catch, including many beneficial insects, butterflies and each other. Mantids are nearly useless for pest control in home gardens because their diets are so diverse. Once I saw a mantis chomping on a bumble bee.

Most of the mantids that hatch from an egg case will die from starvation or cannibalism. Mantids are territorial and by the end of the summer usually only one adult is left in the vicinity of the egg case...one big adult.

I know many people think the only good bug is a dead bug, but a very, very small percent of the insects and related species are actually harmful to us, our plants, structures or animals. Once you get past the "yuck" stage, insects are fascinating to watch. Insects have all the elements of a good science fiction movie. Plus they are in your own backyard and there is no admission fee.

Mantids may not be great pest control, but there are many unsung heroes of the bug world helping us out by eating or parasitizing the bad bugs. Some common beneficials are lady bugs, green lacewings, ground beetles, some flies and even some wasps.

Here's what we can do to encourage the good guys.

Learn how to recognize common beneficial insects. A great reference is the laminated card set "The Good Guys! Natural Enemies of Pests" available through UI Pubs Plus 800-345-6087; 217-333-2007 https://pubsplus.illinois.edu/

Minimize or eliminate insecticide applications. Many insecticides will kill beneficial as well as pest insects. Even natural botanical insecticides such as rotenone can kill beneficial insects.

Plant a variety of flowers and plan a full season of bloom with various flower shapes and sizes and include lots of native plants such as New Jersey tea, golden Alexander, aster, wild bergamot, great blue lobelia, white wild indigo, blanket flower, coneflower, coreopsis, cosmos, goldenrod, penstemon, and sunflowers.

This garden season make a commitment to help out the good guys and to accurately identify a pest before stomping, squishing or spraying.

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