According to several sources, Great Britain is being invaded by hordes of hover flies. We in the Pacific Northwest are seeing our fair share as well. So what is going on?
Hover flies are attracted to many of the same plant species as butterflies and bees, so it is no surprise that they are most abundant in the summer months. In addition, many of the hover fly species migrate as do some butterflies. In Great Britain, hover flies arrive in great quantities from southern Europe.
But the invasion of the hover flies is good news for gardeners since many of the larval forms eat yummy critters like aphids, thrips, and leafhoppers. Others eat decaying plants and animals. The adult forms of many species eat nectar and pollen and, in the process, become good pollinators.
Hover flies are so beneficial that many gardeners plant food plots especially designed to attract them to their patches. Among the plants most attractive are:
- Calendula (pot marigold)
- Convolvulus minor
- Iberis umbellata (candytuft)
- Queen Anne’s lace
Unfortunately, hover flies, like many other invertebrate species, are losing valuable habitat to urban growth and modern farming. Although hover flies often go unnoticed, their ecological importance is significant—something that researchers are only beginning to piece together. Let’s provide them plenty of places to live . . . before they become endangered.
The poster below, prepared by Alvesgaspar and borrowed from Wikimedia Commons, shows a good sampling of the more common hover fly species.