Pest control

During the recent spell of rain, a leopard frog moved into our vegetable gardens. I was glad to see it, in part because I had never seen one before, and also because I knew it was dining on the ants, beetles, flies and other insects we want to keep under control. The frog hasn’t appeared since the return of hot, sunny days, but I assume it is still nearby.

I’ve since learned that leopard frogs are considered an “indicator species,” one that reflects the health (or lack of health) of the environment around it. Once quite common in North America, they began declining in the 1970s, most likely because of acid rain and other pollutants, and they have not yet recovered. So that makes me even happier to have seen it in our gardens.

Since we replaced the expanses of lawn with mixed plantings that more closely resemble the diversity of a meadow, the diversity of the animals, birds, reptiles and insects has also dramatically increased. That’s great for wildlife watching: working in the garden or sitting on the deck, I see 4-5 different kinds of butterflies on any given day. More importantly, it’s a spectacularly effective pest control strategy. In natural areas, no one species balloons in numbers (unless it’s an “exotic” introduction) because natural predators keep their prey under control. But large expanses of a single crop (including grass) don’t offer shelter, camouflage or breeding sites for the predators. Hence the need for repeated applications of chemical insecticides. Instead, we keep some broken clay pots half-buried in the gardens to provide hiding places for frogs, and we have a half-dug small pool that, even unfinished, seems to be drawing them closer. We call it a “muddle,” short for “mud-puddle.”

The leopard frog is joined by several garden snakes who make regular appearances. A particularly large one living under the shed spends a fair amount of time in the squash patch, hiding under the large leaves, and another who appears to be living in a cavity made by a warped board in one of the raised beds. They, too, eat insects and slugs, along with a variety of other prey (including frogs), and every so often, we find a recently shed snake skin to admire.   

Tiny parasitic wasps, damsel flies, soldier beetles and other pest-eating insects are drawn to the gardens by the nectar available in the umbrella-like flowers we plant or leave. Queen Anne’s Lace (wild carrot), a “weed” we selectively leave; cilantro; dill, borage and the mustard are among their favorites. Except the first, all have edible flowers, and they all self-seed liberally so we leave many scattered throughout the garden after weeding out those we don't want. The number of spiders building webs in the garden has increased as well, and daddy-long-legs are everywhere, looking to me like silent sentinels patrolling among the snap pea, squash and bean leaves. There’s one particularly beautiful black-and-white-patterned daddy-long-legs that frequents the squash plants this summer.

Finally, we help the small predators, handpicking slugs, snails, and squash beetles often enough to give the plants a fighting start. Last year we bought ourselves an insect guide to learn to recognize the difference between the soldier beetles, which we want, and the squash vine borers, cucumber beetles and other squash bugs that that we don’t. Earlier this week, we managed to identify and kill two squash vine borers for the first time, hopefully before they had laid their eggs.

For the larger pests, we have Kat, who adopted us the summer we began this project. We had seen her in hiding in the woods for some months until she finally became too weak to hunt. Hunger overcame her fear of humans, and she cautiously ate the food we provided before running off again. Each time we came to the door with food, she flinched as if expecting a kick, but gradually she has relaxed, jumping on a lap to be petted and groomed whether invited or not. When Kat arrived, mouse were living in the attic and walls, rabbits had moved their warrens into the gardens, and voles were tunneling everywhere. It didn’t take long before those inhabitants were gone, and future ones discouraged or killed.  It even seemed that Kat discouraged the deer for the first couple years. My friend, Beth, an environmental educator, says that’s quite possible, since bobcats, a natural predator of deer, are not much larger than Kat.

This entry wouldn’t be complete with a further comment on those voracious, uninvited eaters, since the most frequent question I’m asked by human visitors to the garden is, “How do you keep deer out?”  The answer, like many others we give, is “by using diverse approaches simultaneously.” Until a few weeks ago, we combined Kat patrolling at night with caging for young fruit trees and shrubs and selectively sprinkling DeerScram (a very effective organic powder of ground-up deer parts that elicits an instinctive fear response) sprinkled around their favorite entries to the garden and their favorite plants at the times they most like eating them. Finally, we planted enough to “share” parts of the crop, no matter how frustrating that was. The “timing factor” seemed to work this spring, as the flowering pea plants (apparently a particularly tasty item for deer) remained untouched.

With our gardens expanding, however, it seemed more cost-effective to erect a deer fence. So this year, we invested in a 7.5’ high, plastic mesh fence, and Richard hung it on trees through the woods, encircling a little over an acre around the house and gardens.

Photo credits: Southern Leopard Frog, similar to its Northern cousin, and Garden Snake from Wikipedia. Cilantro in flower and Kat by Margo HIttleman