Some people believe that the only good insect is a dead insect. While it is true that there are some bad bugs out there, there are many more kinds of good bugs doing their part to keep the bad bugs in check. The ratio is actually about 99 percent good insects, 1 percent pests.
I better quickly mention that technically I shouldn’t call them “bugs.” True bugs are in the insect order Hemiptera, and lack hard wing covers. There are 36 other orders of insects.
Ladybugs are among the most visible and well-known of all the beneficial insects. Did you know that there are over 500 different species of ladybugs in North America alone? The adults tend to be orange to red, with no spots to many brown or black spots on their wing covers. The larvae look evil, however, like hairy little orange and black caterpillars. They help though, stalking around on leaves, eating over their weight in other bugs every day. They like sweet aphids but will also eat insect eggs.
Ladybugs are really beetles, in the order Coleoptera. Mantids, including the praying mantis, are predatory beasts. Mantids stalk their prey, seize it, and devour it with sharp saw-like jaws. Mantid egg cases look like miniature volcanic mountain ranges, laid on twigs or even on walls. The young emerge, hungry for bugs, and may even eat unlucky siblings.
Lacewing larvae are perhaps the most prodigious insect eaters. Looking like a little caterpillar with a large pair of wickedly hooked jaws projecting from the front of the head, they are pest killers on the prowl. They feed voraciously on many plant pests, including caterpillars, beetle larvae, bug larvae and scale insects, consuming prey several times larger than they are. Adult lacewings pollinate any number of small shallow flowers, and eat a few pests while they are at it.
In the Southwest, lacewings are not always green. There are brown lacewings that look sort of like a giant mosquito. Don’t kill the lacewings.
If it looks like a bee, and sounds like a bee, it must be a bee, right? Not if it is a syrphid fly. These black and yellow bee-mimics are great for the garden. Adults pollinate flowers, but their larvae are the ones you want. Syrphid larvae are green or gray maggots that feed on aphids and other soft body plant pests. To tell if it is a bee or a fly, check the waist. Bees and wasps are in the Hymenoptera, the wasp-waisted order, and have four wings, while flies have fat waists and are in the order Diptera, meaning “two wings.”
Fly eyes are different too, flat at the back instead of rounded. Many wasps are good wasps, unless you are a bug. Braconid and Ichneumid wasps are straight out of science fiction. Or maybe it’s the other way around, fiction taken from true life. Basically, the wasp mothers find nice, juicy insects to lay their eggs on. The wasp larvae hatch, burrow into the insect, and slowly eat it alive, from the inside. They eat muscle tissues first, immobilizing their food, and leave the vital organs for dessert. Aliens. When they are not looking for insects to support their young, adult parasitic wasps feed on nectar and pollen. You may occasionally find them feeding at hummingbird feeders. There are well over a thousand species of parasitic wasps, each of which attacks a specific kind of host insect.
Ant lions are another insect that have made their way into science fiction. The larvae dig a cone-shaped pit in the dirt and wait for an unwary ant or other bug to walk near. Then they throw grains of sand at the hapless insect until it loses its footing and tumbles into their trap. Lunge. Chomp. The bug is history. (Remember the creature in the pit in “Return of the Jedi”?) Quite unlike their grublike larvae, the adult ant lions look like large mosquitoes.
There is simply not enough space to discuss owlflies, dragonflies, damselflies, snakeflies, mengieds, halictophagids, elenchids, scorpionflies, hangingflies, figitids, ibalids … and so on. “For every flea there is a flea Upon his back to bite him. And so on, and so on, Ad infinitum.”
So let the bugs live in your yard. They provide food for many species of desert birds, lizards, even bats. Besides, they eat the pests, not be the pests.