Kathy Doisy
Garden leader Calvin Miles, from Friendship Garden Club, recently asked me a very good question, “What are the good insects?”
Well, first off, we want pollinators. As I mentioned in my last post about “insect hotels,” these include honey bees, bumble bees, solitary bees, ants, butterflies, moths and some flies. Where this gets tricky is that some butterflies and moths are actually laying eggs so their young can devour your crops. I could go on (and on, and on), but, generally, if you see a butterfly or moth hanging around your cole crops or corn it is probably laying eggs because these plants don’t require pollinators. Of course, it may also just be taking a rest. One rule of thumb is that if it’s a pretty butterfly, give it a nudge to move it along. If it returns and especially if it’s white or yellow, get rid of it if you can.
So, beyond pollinating many of our crops, insects may be beneficial to our gardens by consuming other insects and relatives that damage our crops. There are dozens of these beneficials, so I’m just going to address the ones I most commonly see in my Columbia garden. Then I’ll list some good websites for readers who want more information.
Most everyone knows what a ladybug looks like. Maybe you also know that they help our gardens by eating aphids and other small plant pests. Did you know that immature ladybugs do the same thing? They range from a few millimeters to ½-inch in length. Here is picture of one so you know to leave it alone or move it to a plant with an aphid infestation!
Ladybug larva
Another good type of insect to find in your garden is a praying mantis. There are three species found in Missouri, ranging in size from about 2½ to 5 inches, and in coloration from brown to bright green. These feed on most anything they can catch, even including, on rare occasions, hummingbirds. I’ve seen a picture of this and actually found a pair of hummingbird wings mixed in with the butterfly wings beneath one of my Chinese mantises! Survival of the fittest, right? EEK! That said, put a mantis on your green bean plants and forget about leaf damage.
Praying mantis
Lacewings are another great predator. The adults and young both eat aphids, small caterpillars, mites, etc. (and fortunately not hummingbirds). The adults are about ¾-inch long and may be green or brown. Larvae are about a ½-inch long and brown.
Adult lacewing, left. Immature lacewing, right
Stink bugs…are way too complicated. Generally speaking, stink bugs feed on our crops and damage them by sucking fluids. However, a few species of stink bugs suck the juices out of all
kinds of crop-destroying caterpillars. Unfortunately, even I can’t tell the good guys apart from the pest species without a magnifying glass. While all stink bugs have long, tube-like mouthparts, the predators have a broader tube than the plant feeding types. So, unless you find a stink bug in the process of killing something else, you might just go with the odds and kill any that you see. (If you’re game to try sparing the predatory species, though, read to the end for a couple good guides to common species.)
Green stink bug
Another group of beneficial predatory insects I often see is damsel bugs. There are quite a few species you may encounter. The one I frequently see is brown and about a ½-inch long. These are true bugs (like stink bugs) and, therefore, grab their prey and use tube-like mouthparts to suck the juices from a variety of caterpillars, leafhoppers and other garden pests.
Damsel bug
So that’s just a few of the more common beneficial insects. There are also dragonflies, ground beetles, ambush bugs, assassin bugs, predatory and parasitic wasps, predatory flies, and our non-insect friends the spiders and some mites. To learn more, check out some of the websites listed below.
More information on beneficial insects and how to attract them:
- MU Extension – Increasing Beneficial Insects in Row Crops and Gardens
- Missouri Botanical Garden – Beneficial Insects
- Washington State University Extension – Beneficial Insects, Spiders, and Other Mini-Creatures in Your Garden
- Wikipedia.org – Beneficial_insects
More information on stink bugs:
Community Garden Coalition 