Appears: These flies are most abundant in the summer months.
Beneficial: The robber fly, as an adult, feeds on a variety of insects including bees, beetles, leafhoppers and other flies, typically catching them in mid flight. Their larvae feed on other anthropoids such as white grubs, beetle pupae, and grasshopper eggs. They are considered beneficial, but remember, they do kill and eat good garden insects as well.
More Info:
Size: 9mm – 15mm