Photo: Meadowood Recreation Area, Rusty Moran
During the pandemic we’ve had to cancel our regular wildlife surveys but some long-time participants are going out individually on an ad hoc basis to continue collecting data. Judy Gallagher is one of those folks who also captures photos of what she sees, in particular the less common species. Here are two observations from her most recent survey.
Insects are winding down for the year, but flies still seem to be common. Here are two I saw recently, both at Julie Metz Wetlands.
The Feather-legged Fly is a parasite in its larval form. The adult is about the size of a house fly and the female hovers above plants searching for a Squash Bug or Southern Green Stink Bug on which to lay her eggs. The eggs hatch and the fly larvae feed on the bugs, eventually killing them. This fly is useful as a biological control, and it was deliberately introduced to California to try to control Squash Bug populations around squash farms. Some scientists estimate that as much as 80% of Squash Bugs there have fly eggs deposited on them, but the parasitized Squash Bugs live long enough to still damage crops, so the biological control is only partially successful.
Feather-legged Fly, Judy Gallagher
At first glance one might think this is a tiny wasp, but it's one of the Flower Flies, the Margined Calligrapher, named because the abdominal pattern resembles fine calligraphy. It may derive protection from predation by mimicking a bee or wasp but it's clearly a fly with its short stubby antennae and only two wings. Adult Margined Calligraphers pollinate and their carnivorous larvae eat aphids, so they are a good thing to see in your garden.
Margined Calligrapher, Judy Gallagher