February, 2015

Convergent Lady Beetle

The convergent lady beetle (Hippodamia convergens) is a familiar sight to many gardeners. As one of a large number of lady beetles, or ladybugs, found in the U.S., this native species is not only an important biological control of aphids and other small soft-bodied insects that eat plants, but it is also the one most often sold in nurseries and garden supply stores. The common name comes from the pair of converging white dashes always present on the pronotum (the bit behind the head). The black dots on the orange part are variable; they can be large and prominent or completely absent.

The individual shown above is engaged in the quintessential ladybug activity of eating an aphid. It also happens to be a very wet beetle, as it was raining when the photo was taken. The hard carapace that covers the wings and body acts as a very effective umbrella.

Both the larvae and the adults are predators. They adjust their reproduction to the availability of prey, and a heavy aphid infestation can result in a large population. Once they eat up all the aphids, the adults usually fly away. In fact, this mobility is the main reason why it doesn't work so well to buy lady beetles in a store to release in your garden. The vast majority of the insects will quickly disperse. They will be more helpful to your neighbors!