Don’t Wash away Beneficial Insects
Don’t Wash away Beneficial Insects
When I was growing up in New York state, my brothers and I spent more than a few summer hours picking hundreds of hungry, non-native beetles off of our few fruit trees. With no effective natural enemies, these voracious insects survived their underground grub stage and then thrived until we plunged them into soapy water. While this method didn’t get rid of all of the beetles, we also didn’t harm our trees, beneficial insects, birds, or other animals.
Most gardeners are familiar with the concept of a food chain; a hierarchy of organisms in which each is dependent on the next as a source of food.
Plants, producers, are self-sufficient. They use light energy from the sun, carbon dioxide and water to make their own food through photosynthesis. As consumers, animals can’t make their own food so they must eat plants and/or other animals. Even lowly insects are part of food chains during many stages in their life cycles.
From a young age, children often recognize lady beetles (bugs) by their familiar red and black shells. And many of us know that these beneficial insects eat less desirable insects, like aphids, which devour many kinds of plant leaves.
There are several stages in lady beetles’ and other insects’ lives. If we are not aware of what these stages look like, and what happens during those stages, we can inadvertently interrupt and destroy crucial components of a beneficial food chain.
So, included here are photos of the important larval stages of lady beetles and green lacewings, two beneficial insects we should get to know better.
Lady beetles lay their tiny white eggs (first stage) in clusters or rows on the underside of plant leaves, intentionally near where aphids have gathered, so that their developing larvae (second stage) have a ready source of food.
To watch a fascinating video of this egg- larvae-beetle process, complete with larvae-consuming aphids, visit “A Ladybug Life Cycle” on YouTube.
After watching this video, I realized that if I spray strong streams of water on clusters of aphids, (never spray insecticide poisons on any plants), I am most likely eliminating ladybug larvae as well.
And what a loss that is, because these tiny beetles are prolific. If allowed to develop they can eat up to 5000 insects in their year-long lifetime!
Green Lacewings also have larvae that feed on insect pests including aphids, mealybugs, thrips, juvenile white flies, leafhoppers, and spider mites. Brown and white and about ½ inch long, Lacewing larvae look like little alligators.
Their typical habitat is an aphid-infested cruciferous crop like cabbage, broccoli, kale, arugula, bok choy, collards, and brussels sprouts.
The syrphid fly (hoverfly) is another beneficial insect. Its eggs hatch into green, yellow, orange, or white one-half-inch long maggots that look like caterpillars. They too eat aphids and mealybugs.
To reduce the number of aphids on beloved veggies, start the crop in cooler weather. Plants stressed by hot temperatures and low water are more likely to become infested with aphids. Carefully removing some aphids, while sparing lady beetle and other larvae, helps keep us in vegetables and the beneficial insects in their food chain.
Taking time now to learn to identify the larval stages of local ben-eficial insects will protect them as they work for us in the garden. And intentionally creating varied, visible (at least four feet by four feet) plant habitats will add beauty to our yards and year-round food for friendly insects and birds.
These beneficial, attractive plants can include fennel, buck wheat, penstemon, marigolds, hairy vetch, Queen Anne’s lace, butterfly weed, tansy, dill, angelica, yarrow, caraway, milkweed, lobelia, lemon balm, spearmint, alyssum, daisy goldenrod, marjoram, oregano, and cosmos. Such colorful gardens help assure a food chain buffet for beneficial insects, birds, and humans.
Alison Limoges is a member of Alameda Backyard Growers.