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The Parasitic Wasp in an Organic GardenBeneficial Flying Insects Kill Grubs, Caterpillars, and Other Pests
Attract these beneficial insects to your organic garden, and take advantage of this natural pest control source.
When organic gardeners think of wasps, they often think of the conspicuous mud daubers and paper wasps that build their nests on homes and garden structures. We know these wasps are beneficial, but they can also behave aggressively during the summer months. However, the Hymenoptera order includes a diverse group of wasps that divide their time between nectar rich plants, where they act as pollinators, and garden pests, which act as incubators for the wasps’ young. You can reap the benefits of these beneficial bugs by learning how to identify and attract them to your organic garden. If certain pests plague your garden, you can even buy specific species of parasitic wasps from organic gardening supply companies to aid you in your biological pest control efforts. Attracting Parasitic WaspsAlthough organic gardeners are concerned with parasitic wasps as a biological pest control agent, these beneficial insects need more than just your aphids and caterpillars to sustain their populations. Parasitic wasps use garden pests as nurseries for their young, but the adults need rich sources of nectar to feed on. Without a nectar source, the adults emerging from their insect hosts will simply fly away to find food. Parasitic wasps have tiny mouthparts, so they appreciate shallow flowers with accessible nectar. You can please your parasitic wasp population with plantings of sweet alyssum, fennel, yarrow, or a few carrots left to flower in the vegetable garden. Control Beetles and WeevilsIf Ichneumon wasps aren’t the easiest to identify in the garden, that’s because there are more than 8000 species in this family in North America alone. They parasitize the grubs of many beetles and weevils, as well as using caterpillar hosts. Although Ichneumon wasps exhibit many colors, you may notice the long ovipositors of the female extending well beneath her abdomen like a reverse pair of antennae. The wasps use this anatomical feature to deposit eggs on hosts hidden in tree bark. Control Cabbage Loopers, Armyworms, and CutwormsBraconid wasps are black or brownish wasps with antennae almost as long as their bodies. These wasps are partial to caterpillars as hosts, but some Braconid wasps parasitize aphids and beetles. If you’ve dealt with cabbage loopers, armyworms, or black cutworms in your organic garden, you should celebrate the appearance of Braconid wasps. All that’s left of a caterpillar parasitized by a Braconid wasp is a mummy-like case; the wasp larva completely consumes the host’s internal organs. Control Corn Borers, Spruce Budworms, and Tobacco BudwormTrichogramma wasps are the tiny predators with a long name that every organic gardener should familiarize himself with. Trichogramma wasps are parasites to many moth and butterfly eggs, therefore preventing destructive caterpillars from ever hatching. This parasitic wasp includes at least nine species raised in commercial insectaries for pest control in crops including apples, corn, and almonds. You might never notice this beneficial insect at work, as the largest of the species is smaller than two millimeters. However, if your petunias have ever vanished overnight after a tobacco budworm feast, you know the value of Trichogramma parasitic wasps in your garden. Sources: NC State University College of Agriculture & Life Sciences Texas A&M University Department of Entomology
The copyright of the article The Parasitic Wasp in an Organic Garden in Organic Gardens is owned by Jamie McIntosh. Permission to republish The Parasitic Wasp in an Organic Garden in print or online must be granted by the author in writing.
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