The winner of today’s photography challenge is the weird bug that I noticed on the side of the house. Luckily, there is an entomologist in the family and he was able to identify the insect—it is some type of robber fly.
Basically robber flies are opportunistic predators that feast on a variety of different invertebrates including other flies, grasshoppers, dragonflies, wasps, bees, and even spiders. Robber flies have a broad worldwide distribution (though they’re not found on the Hawaiian Islands).
Robber flies have saliva that contains both neurotoxins and proteolytic enzymes, and when they inject it into their prey—they have a liquid meal to consume once they return to their perch with their stunned, liquified prey. If a robber fly bites you (if you’re irritating them)—you’ll end up with a nasty, painful welt due to the contents of their saliva.
The life cycle of the robber fly takes about one to three years to complete (from egg to mature, mating adults), as most of their life is spent in the immature forms (which are still predators to other larvae and immature insects).
They can be consider both beneficial and irritating in terms of what prey they go after—it’s good that they target wasps, hornets, grasshoppers; but currently it isn’t helping the honeybee populations when they’re eaten by robber flies (though honeybees are a very small portion of the diet of robber flies). They will go after what is in the area, so it is a balancing act—hope they’re out before the bees show up (or that they’ve eaten and are no longer hungry).
I will be keeping my eye out this summer to see if I can spot any more of these unique looking flies in the backyard.