Transcript:

Today on Animal Fact Files we’re discussing robber flies. Robber flies are also known as assassin flies however this could be confused with assassin bugs, which are different animals, so we’ll stick with “robber fly” for this episode. These insects are called robber flies because of their predatory behavior. They are true flies meaning they have only one pair of wings - this is true for all living flys. Robber flies are relatively large flies ranging from half an inch to more than an inch (13-25mm) long in body length. There are thousands of species of these flies and they’re found all throughout the world with the exception of Antarctica. Robber flies spend most of their time in plants or buzzing along the ground while their larvae actually live in the ground or in decaying organic matter like leaf litter and rotten logs. Habitats to robber flies include grasslands, open sections of woodlands, marshes, and sunny spots along ponds and streams.

Robber fly larvae hatch from eggs and go through a few developmental stages before pupating and emerging as adults. During this time they’ll eat organic material, grubs and other arthropod larvae, as well as arthropod eggs. So robber flies have an egg, larva, pupa, and adult stage meaning these animals undergo complete metamorphosis. The complete robber fly life cycle takes over a year to complete.

Robber fly adults are mostly active during the warmer parts of the year depending on where they live. These insects often perch on the stem of a plant in an open area where they can survey the surrounding area for prey. Robber flies are predatory animals and they’ll hunt down other arthropods such as wasps, grasshoppers, bees and more with some of these prey items reaching sizes larger than the robber flies! Robber flies are able to catch animals in the air with their speed and agility. In fact, in the case of beetles, this is one of the only ways that robber flies can get past a beetle's hardened wing covers - while in flight beetle wing covers are open! The fly grabs hold of a prey animal with clawed legs and injects it with venom to paralyze it and enzymes to begin the process of breaking down its insides - this is similar to how a spider’s bite works. Robber flies do not drink blood like mosquitos so they do not actively seek out humans - however they will deliver a painful bite to a person if they’re mishandled. After a successful catch, the robberfly will return to a perch, typically the same from which it started, and enjoy its spoils.

In turn, robber flies have to watch out for mantids, spiders, birds, and even other robber flies! While robberflys are generally consider beneficial because they eat pest species, they’re also known as bee killers because they can take out honey bees. Some robber flies even mimic bees - but they can always be told apart by their single set of wings!

For more facts on robber flies, check out the links in the description. Thank you to Ian, Mike, and Marvelous for today’s request! Give a thumbs up if you learned something new today, and thank you for watching Animal Fact Files!