Caterpillars are the larval form of butterflies and moths, and their main task in life is to eat. If left unchecked, they can damage gardens, commercial crops and even forests. One way to control caterpillars is with poison, but nature has a safer way that helps to keep these pests under control. certain species of wasps kill caterpillars, either by parasitizing them or by hunting them down.
About Parasitic Wasps
Several kinds of parasitic wasps, such as the Cotesia congregatus and the Hyposoter exiguae, target caterpillars. These wasps use the caterpillars as feeding stations for their young by laying their eggs directly on or inside of the living caterpillars. When the young wasps hatch, some emerge from inside the caterpillars' bodies and others from cocoons attached to the outside. Those that developed inside the caterpillar devour him as they grow, while those that hatch from outside will use his body as nourishment after they’ve hatched into their larval stage.
Despite the fact that the caterpillars will live for a time after they’ve been parasitized, when they have been attacked by a parasitic wasp, they don’t have long. Caterpillars grow weaker as the young wasps grow, and eventually the caterpillars are no longer able to carry on. When the wasps hatch, the host caterpillars die. This not only stops the parasitized caterpillar from causing any more destruction, it also prevents him from ever reaching adulthood and breeding, thus preventing the dozens or even hundreds of young he might have produced.
About Predatory Wasps
Paper wasps of the Vespidae family are another group of killer wasps that commonly interacts with caterpillars. These insects hunt down and kill different kinds of pests, but their most common prey is caterpillars. When they’ve killed one, they’ll chew him up and roll him into a ball so they can transport the victim back to their nest. There they feed the dead caterpillar to their young. Paper wasps hunt constantly so they have a steady supply of food for the nest.
Adding Wasps to Home Gardens
It’s possible to buy parasitic wasps from garden supply stores that deal in beneficial insects. Before buying these wasps, make sure you have the right kind of habitat for them, such as nectar-rich flowers, so they can immediately settle in and begin to hunt caterpillars. Their young eat caterpillars, but most adults feed on plant nectar. The predatory paper wasps are not offered for sale, since these can become pests when they set up housekeeping close to human habitation. They will sting people and animals repeatedly if they feel that their nest is threatened.
- Ohio State University Extension: Cabbage Worms
- Toxic Free North Carolina: Organic Solutions for Cabbage Loopers and Cabbage Worms
- University of California Integrated Pest Management: Parasites of Insect Pests
- University of Illinois Extension: Gypsy Moth Damage
- North Carolina State University Dept. of Entomology: Paper Wasp
- Galveston County Master Gardeners: Paper Wasps
- Michigan State University Extension: The Tomato Hornworm and the Tobacco Hornworm
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