Good bugs, bad bugs
Many gardeners seem to think that any UFI (unidentified flying insect) is a potential threat to their tomatoes or the spinach. When in doubt, they swat it, squish it or submerge it. But most bugs are not bad -- and many are helpful.
We all know that lady bugs are good. They eat aphids and in fact, some enterprising businesses are selling lady bugs by the thousand. My advice? Don’t bother buying them. If you’re not spraying your flowers and vegetables with insecticides, you will naturally have some ladybugs and other aphid eaters. Of course insecticides will throw off the balance of nature, and the pests may dominate. But a good healthy garden should attract beneficials like ladybugs in the quantities that you need. Bring in a thousand? They might fly away the same day.
According to the lovely little guide book, "Good Bug Bad Bug: Who’s Who, What They Do, and How to Manage Them Organically," by Jessica Walliser, a ladybug can eat up to 5,000 aphids in its lifetime. But there are plenty of other good bugs. This book, by the way, is simple, well illustrated and sturdy enough to take to the garden. I recommend it.
The assassin bug is just that: a voracious predator that will eat cabbage worms, potato beetles, cucumber beetles, cutworms, earwigs, Japanese beetles, bean beetles, tomato hornworms, and more. They are generally black, and about half an inch long with a broad body and bristly front legs. They have a sharp curved beak they use to penetrate other insects, allowing them to inject a poison to kill them and turn their insides into a "smoothie" they can drink. They can sometimes pierce human flesh if handled roughly.
Lacewings are beautiful green flying insects with diaphanous wings. You’ve probably seen them on your window screens, attracted to the lights -- they’re about an inch long. But it is their larvae that do they work in the garden -- they eat about 100 aphids a day! The larvae are brown and white with big mandibles for grasping prey. They are half an inch long, and fast moving. The adults eat nectar and pollen of flowers and weeds including dandelions, Queen Anne’s lace and goldenrod so a few weeds are good to have -- along with plenty of flowers.
Parasitic wasps are generally small -- from 1/32 of an inch to half an inch -- but do great work. There are some 200 different kinds, according to "Good Bug Bad Bug." Many have noticeable ovipositors for laying eggs, but don’t be confused and think they are stingers -- these beneficial insects do not sting. They generally lay their eggs in the bodies, larvae or eggs of other insects. Once their eggs hatch, the young parasitic wasps feed on their prey.
One type of parasitic wasp feeds on the tomato hornworm. If you see small white "grains of rice" on the back of a hornworm, these are actually larvae of a wasp. Don’t kill the hornworm! Just move it off, away from your tomatoes, and let the wasp larvae do their thing. Like the lacewings, the adults feed on nectar and pollen, so a diverse garden with continuous blooms is a good attractant.
One of the things I like about the book "Good Bug Bad Bug" is that it offers many solutions to an insect problem. Row cover, a breathable spun fabric, is offered as a solution to striped cucumber beetles, and it reminds the reader that cukes are insect pollinated so you can’t keep it on once your vines start to produce blossoms. The book also suggests interplanting with marigolds, catnip or tansy or putting out yellow sticky cards to catch the culprits. Mulch, the book says, will help keep females from contact with the soil where they lay their eggs, too. I didn’t know that.
Potato bugs are my current nemesis. I plant my potatoes much later than my neighbors (in late June) which often means the bugs are already busy by the time my spuds come along. This year they have found me anyway. Every day I go down the row of potatoes, flipping the foliage over to look for adults and orange egg masses underneath the leaves. If I spot eggs, I remove that part of the leaf and put it in soapy water. This sounds tedious, but is actually just a five-minute job for my 65 plants -- and it makes a huge difference.
Diligence counts: I skipped a couple of days of patrol, and found potato bug larvae eating my plants. And picking 50 larvae is a lot more work than removing one leaf. So I shall keep up my vigilance. And if the larvae seem to be winning, I can always spray a biological control called Bt. This is a bacterium that will control them, but damage nothing else. But not all Bt is the same: ask for one that controls potato beetles (San Diego or tenebrionis).
Try to get over your aversion to bugs in the garden, if you have one. Just because a bug is unknown to you is no reason to squish it. It may be an assassin bug, ready to help you!
Henry Homeyer is the author of four gardening books. His Web site is www.Gardening-Guy.com. He is also a garden designer, gardening coach and public speaker.
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