7 ways to maintain your garden with wasps and hornets

While wasps and hornets are often seen as pests because of their stings, these insects are important for the garden as both predatory insects and as pollinators. Here's how wasps and hornets help your garden and how you can keep them around while minimizing their menace.

Wasps comprise a large family of insects that includes hornets and yellow jackets.

• All are fierce predators of many common garden pests.
• Wasps and hornets control garden pests by eating larvae of other critters.
• Some members of the family, unfortunately, also damage fruit and deliver painful stings.

Yellow jackets and other wasps prey on fly larvae, beetle grubs, ants and caterpillars.

• If you think their benefit to your garden outweighs the risk of getting stung, don't destroy their papery nests unless they're close to outdoor living areas or someone in the family is allergic to insect bites.
• Yellow jackets nest in the ground and can make mowing dangerous. Spray a wasp-killing aerosol pesticide into the nest at night, when the wasps are at rest.

Many beneficial wasps are so small — usually less than six millimetres long — that you might not be able to see them. But you can sometimes find their handiwork.

• All beneficial wasps are parasitoids, meaning that they lay their eggs on an insect host, usually on eggs or larvae.
• The developing wasps then form cocoons on the host. If you see a grub or caterpillar with small, ricelike pouches on it, you have beneficial braconid wasps in your garden.

You can buy beneficial wasp eggs from mail-order insectaries and garden catalogs.

• Follow directions for releasing them; some wasps should be set loose over a period of several weeks.
• Don't bother to buy them unless you're sure the pests they use as nurseries are in your garden.

Encourage beneficial wasps to stick around by growing the adults' favourite nectar sources, which include numerous flowers, such as goldenrod, clover, coreopsis, marguerite, sunflowers, yarrow, coriander, parsley and tansy.

• To avoid stings, don't use scented products when you work in the garden, including perfume, scented sunscreen or hairspray.
• Also avoid light blue or yellow clothing, and work outside in the evening, when wasps are less active.

To keep wasps off fruit, cover ripening fruits with muslin or pantyhose tied at both ends, right on the tree.

• To get rid of yellow jackets that appear from unknown places, try this: cut the top off a plastic bottle and invert it inside its base to make a funnel, securing the edges with tape if necessary.
• Pour sugared water into the bottle and hang it in a tree or simply set it where yellow jackets are active.
• The wasps will climb in to reach the liquid and will either drown or be unable to climb out.

Wasps and hornet can be a nuisance and even sting, but it's also possible to live with them in harmony, and have them do some pest control for you in your garden.