The natural reaction of most humans when confronted with an unknown wasp or stinging insect is to be suspicious and even a little nervous. The sight of a stinger brings a knee-jerk reaction in our mind; trained from the accidental encounters with yellow jackets, bald-faced hornets or the occasional honeybee (All the worse for the poor honeybee, whose demise is guaranteed through the expenditure of their only defense). But most stingers were not created to be used in deterrence of human intruders. Many were designed as biological weapons to be used against other insects. Stingers could be considered modified reproductive devices used to paralyze a host before inserting its eggs into the host’s body cavity (Hosts are often aphids or moth caterpillars). Beneficial wasps are known as parasitoids because of this reproductive strategy. For this, we should begin to consider wasps and a variety of other insects as our allies in the war against garden pests.
If you have ever over-wintered leeks and allowed them to flower the following year, you have seen how attractive allium flowers can be to beneficial wasps. There have been days at our farm where more than 20 different wild species have shown themselves on these bulbous, beautiful blossoms. Although some of the wasps we noticed looked downright intimidating, their primary interest for visiting was to feed on nectar. Providing nectar sources is the easiest way to keep and retain a large diversity of beneficials in the garden.
Alliums aren’t the only flowers that can be used to attract beneficials to the garden. A very common bedding plant; alyssum, is another attractive nectar source for beneficial insects; primarily hover flies (also known as syrphid flies). Hover flies are hunters, used to control both aphids and mites. Phacelia is another great source of nectar for wasps, hoverflies and pollinators such as bees (both wild and domesticated).
The key to keeping a healthy population of helpful insects in your garden is to provide a nectar source throughout the entire growing season. As one source wanes, another should take its place. The more sources you offer, the more babies these benificials will have and the fewer problems you will have with pests in your garden. The following link will provide more information on identifying insects that are helpful in the yard and home garden: http://cru.cahe.wsu.edu/CEPublications/EM067E/EM067E.pdf . Of particular note; the best way to keep a healthy population is to avoid the application of broad spectrum, synthetic pesticides.