Last week while working outside a dark cloud came overhead, and before I realized what was happening, it was sleeting. The next morning while walking to my car, it was snowing. Thankfully the rest of the weekend was nice. The reason for this introduction is because given the spring we are having, it’s hard to know what and when to plant.
Many more gardeners, including the Chisago County Master Gardeners, are becoming more aware of beneficial insects. All of us need to learn how to identify beneficial insects in their different life stages before we destroy them because they are insects.
Most of us know that lady beetle adults fed on aphids, but did you know that lady beetle larvae consume many more aphids than the adults?
Most of us, however, would not recognize the black, alligator-like larvae, and our first reaction would be to get rid of them.
Many beneficial insects are already present in and around your yard. One of the easiest ways to help them survive is to cut down your pesticide use. Pesticides kill many kinds of insects, not just the one you are targeting, as many of the beneficial ones will lay their eggs near aphid colonies. Also, scientists have recently discovered that adult parasitic wasps feed on the honeydew produced by aphids.
One way to attract beneficial insects is to leave a few pests as food. If you can tolerate a little damage initially, you will soon have lacewings, lady beetles, flower flies and parasitic wasps hovering around your plants. They will switch to other aphids that are more serious pests (such as rose aphids) if infestations occur.
Flowers produce nectar and pollen, which are used as food by the adults of many beneficial insects. An example is the annual flower, alyssum, which attracts flower flies and tiny parasitic wasps. By supplying food for the adults, you will have more of the beneficial larvae.
Flower fly adults are often called hover flies because they hover around flowers, performing important pollination functions. They are yellow and black and are often mistaken for bees or wasps, but they do not sting. They have only two wings, while bees and wasps have four. The larvae are pale green legless worms that feed on aphids, thrips, and other plant-sucking pests.
The larvae of parasitic wasps eat a number of different pest insects, such as caterpillars, leafhoppers, or cicadas. Parasitic wasps generally do not sting unless they are threatened or handled. They use their stinger to lay eggs inside other insects.