Robber Fly—A Dedicated Predator in Your Gardens

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There are nearly 1,000 North American species of robber flies, with more than 100 species in Florida.

Many are stout and very hairy. Some resemble bumble bees, while others have a damselfly appearance. They range in size from 3/8 inch to 1 1/8 inches (1 to 5.5 cm).

The females tend to have slightly broader abdomens than males.

Most robber flies are brown, gray, or black.

They have a characteristic divot on the top of the head, between their compound eyes.

They have bristled legs that are long and strong legs that aid in capturing prey.

They live in grasslands and shrublands and prefer areas with many flowers, where their favorite prey, small bees and wasps, live.

Predator Behavior

Adults attack pests like grasshoppers. Much of their prey consists of plant-eating insects.

However, they also attack beneficial insects, including wasps, bees, dragonflies and some spiders. Certain species of robber fly are known to deplete the populations of places where honeybees are raised.

The adults kill prey with toxic saliva, which is injected through their short nose. The dissolved tissues are then sucked back up through the nose.

Eggs are laid on dead plant stems. In the soil or decaying wood, the larvae develop and prey on other insect larvae.

From Robber Fly to Beneficial Insects R-Z