Choose plantings that attract beneficial parasitic wasps

Published: Thursday, March 20, 2014 at 11:59 AM.

During the last stage of development, wasp larvae chew their way out of the host and spin a silken cocoon, in which they pupate. Almost one week later, adult wasps cut an escape hatch in the top of the cocoon and fly away, searching for another host in which to lay their eggs. It is not until the last adult wasp flies away that the host caterpillar will die.

Identifying wasps

While you may not have seen a parasitic wasp, you have likely to have seen their fluffy white cocoons on the backs of caterpillars. Tiny white cocoons on the backs of hornworms are an indication they have been parasitized by a wasp. Hornworms with these white cocoons should be preserved on the plant, or moved to another area of the garden where the wasps can mature and continue to benefit the garden.

Attracting parasitic wasps with flowers

Although honeybees and butterflies get a lot of attention as pollinators, as a group, parasitic wasps are arguably the largest and most effective at pollinating flowers. Because they do not feed on caterpillars, wasps must supplement their diet with pollen and nectar, just like honey bees. If you want to attract pollinating wasps to your garden, consider adding plants that flower throughout the year. Many of the plants that are beneficial for bees and butterflies are also great at attracting parasitic wasps. Marigolds are a great summer annual that attract wasps, as do cowpeas, and white clover, which is rich in high-quality sugars. If you grow herbs, consider adding fennel, rosemary, dill, or lavender to the garden as these plants are highly nutritious to foraging wasps.

With all of the pests that plague the garden throughout the year, it is comforting to know that beneficial parasitic wasps are out in force. By planting and maintaining flowering plants that provide nectar and pollen, you can do your part to help maintain natural, biological pest control.

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