Good And Bad Bugs

When I was growing up there were only two known “good” insects.

Everyone knew that ladybugs, or lady beetles as they were also known, and praying mantis were the two bugs that you always wanted in your garden. All others, with the exception of bees, were the demons of the orchard and the garden and had to be eradicated.

Many of us bought ladybugs and praying mantis, even had them delivered by mail. And if they survived the journey, they were released into our gardens.

The rest of the bugs, except for the bees, were routinely sprayed with a myriad of chemicals to ensure that they didn’t eat our flowers, veggies and our fruits. But we were so very, very wrong.

When we sprayed we invariably killed the bees, and often even the birds and nearby fish. We also had no clue that the ladybugs that we released simply flew away and that the stage that this beetle eats other insects is in its “non-flying” stage when it’s referred to as an aphid lion—an ugly but voracious eater of aphids and others.

We weren’t quite right about the praying mantis either. The egg cases that we bought—which contained hundreds of tiny mantids that we thought were just waiting for the right time to emerge from the case and form a chain of mantids that would string to the ground where they would grow from teeny, tiny specs to huge, winged bug-eating machines that every property needed—never produced the teeny, tiny babies. And those few that did produced cannibalistic insects who survived by eating each other as much or more than the other insects in the garden.

Think about it. In all the years that you’ve been gardening, how many praying mantises have you seen on your property? One, two? Ever wonder why there are never more?

So to some degree, we’ve been duped. And based on the ladybug containers sold at the garden center cash registers we’re still not really on the ball.

It’s time to wake up and understand the world of beneficial insects. There are actually more than two—it’s more like hundreds—and I suspect that some have yet to be discovered.

There are tiny wasps, miniature mites, benevolent beetles and a host of insect characters that we now use to our benefit. We now know that these “beneficials” can be easily wiped from our garden through the indiscriminate use of pesticides that don’t discriminate between the good bugs and the bad ones. These are known as the wide- or broad-spectrum insecticides, such as malathion, the Sevin brand, and to a slightly lesser degree the nicotinoids, such as Merit.

But we’ll get to the insecticides in a few weeks.

The first parasitic wasp that I became familiar with was the braconid wasp that lays its eggs inside the body of the tomato hornworm—a caterpillar that can devour a large tomato plant in just a few days.

The hornworms can often be found with tiny white projectiles growing along their backs. These are the larvae of the wasp that emerge into the hornworm as they feed on it and mature. In a few days, the hornworm is history and the tiny wasps grow and fly off, then mate, and the females then search for other hornworms to begin a family all over again.

Hornworms that have these white dots should be left alone so the wasps can mature and help you out once again.

The next beneficial that I met was also a wasp. This one, the

encarsia formosa

species, has a thing for whitefly eggs.

If you’ve ever bought a poinsettia, it probably had a close encounter with this microscopic wasp. For ages the whitefly has been the bane of poinsettia growers and it’s almost endemic to the plant. But late in the 20th century, the greenhouse whitefly (there are actually several species) was rapidly becoming resistant and immune to our pesticides.

Researchers discovered that the female sex of this tiny wasp, which is smaller than .6 millimeter long, could parasitize between 50 to 100 whitefly eggs in a greenhouse with no pesticides and render the whitefly useless as the wasp offspring developed inside the whitefly egg. It was a rather remarkable discovery, and within several years greenhouse growers could buy cards onto which encarcia eggs were “seeded.” These cards were positioned inside the greenhouses on regular schedules and like clockwork the tiny wasps emerged from the cards to begin their lifelong goal: finding whitefly eggs to parasitize with their own progeny.

The last beneficial that I met was not a true insect but belongs to a group of microscopic worms that we call “entomopathogenic nematodes.” There are several varieties that can be used to control Japanese beetles, rose chafers, fleas, cutworms, gnats and ants.

This is a developing science because getting the nematodes to the target insects has proven to be fairly complex and the right species of nematode has to be used on the specific target under specific conditions. But the one time I used nematodes on a Virginia lawn to control Japanese beetles I really lucked out and became a believer.

Others have not been as successful but the right person with the right knowledge can use nematodes and get good results. Unfortunately, I don’t think this is a project for most homeowners but the products are available to you and in 10 years many of you may be spraying your lawn and garden with nematodes.

If you’ve got hemlocks on your property you probably know about the hemlock woolly adelgid, an insect that was predicted to wipe out our hemlocks when it appeared in the east about 30 years ago. Two things happened though.

First we realized that in our heavily fertilized landscapes the simple act of not feeding hemlocks reduced the adelgid problem. The next thing that was noticed was that in the wild there were large stands of hemlocks that seemed unaffected or only mildly affected by the adelgid. The reason? Naturally occurring predators that occurred in the wild and in hemlock forests, controlled the insect.

In our landscapes, however, our constant haphazard spraying for all insects simply killed these beneficials and not the adelgids. But simple and safe controls—such as the use of horticultural oils, elimination of nitrogen fertilizer and the encouragement and introduction of adelgid predators—seem to have saved our hemlocks and now we even find them being replanted in the landscape.

Beneficials can and should play a big role in your garden and landscape. You can learn how to protect beneficials, how to encourage them on your property by planting flowers and plants that attract them, and even how to introduce and reintroduce them to your garden.

There’s a great piece on gardenguides.com on beneficials. Additionally, Jessica Walliser has written a very good spiral-bound book called “Good Bug Bad Bug: Who’s Who, What They Do, and How to Manage Them Organically (All You Need to Know about the Insects in Your Garden)” that’s under $15 and in its second edition.

I’ve also got a few other links to some great articles. So if you want to bring the good bugs in and get rid of the bad ones without pesticides, email me a note and I’ll send you the links.

Keep growing.