“I think I’m beginning to interpret your growls,” Diane said, “Has something been eating our squash again?” I was waist-deep in the Patty Pan vines. At that moment my audible (if incoherent) curses were actually directed at my own ill-conceived attempt to make the most of our fertile soil by planting the plants so close together that harvesting their fruits required wading through a tangled jungle of leaves and stems. But minutes later, I was shaking Japanese eggplants at the sky. Narrow, gently curved, and a dark glossy purple, their bottom halves had been entirely chewed off. “Woodchuck,” I growled. “Argh!”
Agricultural pests. They come in all shapes and sizes, from the microbial to the four-legged. By the time I began to garden as an adult, I knew I wanted to do it organically. I’d read enough about conventional pest-killers to be deeply uncomfortable using them. Some were neurotoxins, others suspected carcinogens. And as anyone who has ever seen me paint the side of a barn can attest, I tend to, well, “immerse myself” in my work. It’s a given that anything I spray on my plants is going to end up all over me as well. Covering myself in neurotoxins and suspected carcinogens didn’t seem like a great idea.
But what to do about pests? The organic gardening books told me to focus on growing healthy plants rather than killing insects and disease-causing microorganisms. It made sense that healthier plants would be more disease-resistant—when I took good care of my body I was less susceptible to colds and flu. But what about tomato worms, cabbage loopers, cucumber beetles? Cultivate a diverse and healthy ecosystem, the books said, encourage beneficial insects. After 15 years of trial and error, I can confirm that when my soil is healthy and the plant and insect populations in my garden diverse, pests do seem to appear in smaller numbers and the plants are better able to withstand their damage.
From time to time, however, pests still threaten to destroy a much worked-for crop. This year we’ve encountered only a few insects and diseases that have required our intervention. The two green worms familiar to many gardeners, the tomato hornworm and cabbage looper, we’ve combatted with a naturally occurring bacteria (Bacillus thuringiensis, also known as BT) nontoxic to humans, but fatal to caterpillars. Less successful has been our attempt to slow the spread of downy mildew in our cucumbers with an organically-approved formulation of copper. Though we are still harvesting a bumper crop, this fungal disease is causing the leaves to die back, and the resulting energy depletion will eventually curtail the plants’ abilities to produce fruit.
A pest previously unfamiliar to me appeared this summer, a soft-bodied grey insect apparently determined to turn our Swiss chard into green lace. I’ve not been able to identify this creature as yet, but after an initial application of BT failed to have any noticeable effect on its numbers, I decided to go after it with our strongest organic bug killer, pyrethrum, a broad-spectrum insecticide found inside a particular type of chrysanthemum flower. As I aimed the nozzle of my spray bottle over the holey leaves, however, something caught my eye. Jutting from the underside of a leaf on a slender stiff thread was a tiny green egg. I turned over the next leaf. Another egg on a thread. And another. Lacewings.
Like ladybugs and praying mantises, lacewings are rapacious insectivores. It is surmised that the reason the adults lay their eggs singly and on stalks is to keep the larva from devouring their brothers and sisters immediately upon hatching. My pyrethrum spray might knock out one generation of those mysterious grey chard-munchers, but it would also destroy the lacewing eggs, which left alone would hatch a generation of black larva eager to suck the juices of my chard pests without any help from me. I put my spray bottle away.
It’s been a couple of weeks since the lacewings have hatched and the Swiss chard looks healthier, though there are still some holes in the leaves where insects have been nibbling. On my walk through the fields this evening, I spied a praying mantis climbing in a clump of tall grass. Begging its pardon, I gathered it carefully in my shirt and carried it back to the vegetable plot. I don’t think it will do anything about our woodchuck problem, but perhaps it will finish the job the lacewings started in the chard. Afterward, maybe it will wander over to the beans and snack on some Japanese beetles.
Here is one pest I let munch away in the carrots and dill. Black Swallowtail butterflies are too pretty to kill!