The battle of the bugs

Ladybug larvae chowing down on aphids. — Gilles San Martin/Flickr

An attack by the creepy-crawlies of this world can turn the most benevolent gardener into a raging one-person militia, armed with spray bottles, chemical weapons and a righteous vengeance.

You didn’t raise those beautiful roses to feed them to aphids, nor did you set out those tomato seedlings expecting them to be ambushed by fat green caterpillars with attitude. When perfect leaves and flawless flowers are shot through with holes, and something six-legged scuttles away from the scene of the crime unrepentant, it’s likely to raise your dander.

But gardener, stay your hand. Before you reach for an all-purpose insecticide to blast the garden (and yourself) with a lethal spray, spend a moment in rational reflection. Let the fear and loathing pass and remember that the cardinal rule of doctoring is first, do no harm.

If you plan to do battle with the bugs, consider how badly you are outnumbered. Eric Grissell, author of the highly instructive “Insects and Gardens” (Timber Press), calculates the estimated weight of all insects at 27 billion tons, or about six times the aggregate mass of the earth’s human population. That makes those thuggish, buggish characters the dominant animal life-form; it’s their world, and we’re just living in it.

No matter how much time and energy you may lavish on your garden, you are not going at it 24/7, as the insects are. If you are like most people, you can only correctly identify a handful of the roughly 1.5 million insect species afoot and aflutter in the land. They’ve had something like 400 million years to perfect their way of life, which makes you, dear gardener, a brash upstart, a Johnny-come-lately.

Happily, only about 10 percent of the insect orders have designs on that beautiful garden of yours. The rest may want, as fervently as you do, to visit death and destruction on their leaf-eating, sap-sucking, root-chomping herbivorous brethren. Spraying with a broad-spectrum insecticide is just as likely to do in these predators, which may produce but a single generation per season, as it is to kill the target insect.

Caterpillar parasitized by braconid wasp eggs. — Babbletrish/Flickr

Prey is always more abundant than predator in any food chain (think of the vast wildebeest herds and the mere handful of big cats that feed on them). The pest may rebound with vigor in the absence of predation and be more of a problem than before. It’s so easy to achieve bad results with good intentions, and in the natural world, Hardin’s Law (articulated by biologist Garrett Hardin) always applies: “We can never do merely one thing.”

The spray that kills the aphids may do in the lady beetles that feed on them. Squashing the blister beetle eliminates their larvae, which consume grasshopper eggs. Swatting the braconid wasp may remove a key enemy of caterpillars, beetles, aphids, flies and hornworms. The fearsome-looking assassin bug, which may in fact bite you if disturbed, is really looking for a nice fat beetle, caterpillar or leafhopper to paralyze and eat.

We may think we want fewer “bugs” in our garden, but in fact, we want more of them. When insect life abounds, a balance is struck between plant-attackers and their nemeses. We are — I am — woefully ignorant about the hidden interactions among the leaves and in the soil of gardens we believe we know as well as the back of our hand.

As a human in Bugland, what do you do when your prize (fill in the blank) is under attack? You could do nothing — the problem might resolve itself. You should, by stealth and with magnifying glass if necessary, endeavor to identify the enemy. When you know the name of the beast, try controls that target the trouble-maker and only gradually accelerate into toxic warfare.

This does require investigation, research, time and effort. It may send you to your county office of the Rutgers Extension Service, where diagnosis and advice is free. But it may also make you more sensitive to the web of life that thrives in your garden without your permission, and whether you like it or not. You won’t beat them, those insects, not in a million years. They’ve been at the game of life far longer than you.