Hello again! I've been away a while because I had a pretty big life event: we had a little boy! He's the sweetest little thing but needed lots of care. Now he's big enough to come on walks with us and he seems to be content so I've returned to writing.
This time, I'd like to discuss robber flies. Firstly, they are my partner's favorite insect which got me to really look into them in the first place. We've been searching for them all summer and one just happened to land on our window at home one afternoon.
Robber flies are in the family Asilidae. They have a waspy kind of shape, a short proboscis with a sharp, sucking hypopharynx to consume its prey. They also have three ocelli on the tops of their heads between their two large compound eyes. Their legs are long and spiny. My favorite part about them is their mystax which translates to moustache! It is thought to help protect the robber fly's head and face when they're struggling with their prey. They're sometimes confused with wasps or mosquitoes because of the similar body shape but I usually tell them apart by their moustache and halteres!
They eat other insects and are ambush predators. In fact, they're called robber flies because they usually snatch their prey right out of the air! Their diet is the most vast I've seen in a fly. They eat: flies, beetles, butterflies and moths, various bees, ants, dragonflies and damselflies, ichneumon wasps, grasshoppers, and some spiders! Some do specialize in smaller prey though and appear smaller and more graceful to compensate. They don't seem interested in humans but will deliver a painful bite if handled improperly. Below is an example of a much smaller species which I would assume captures smaller prey and is more graceful in flight.
The way they consume their prey is quite interesting. The fly grabs their prey right out of the air and then stabs it with its proboscis. During this time, the prey is injected with neurotoxins and proteolytic enzymes which paralyze and digest them at the same time, slurping up the liquid. I like to compare the process to eating a tube of gogurt!
How do they reproduce? Females have an ovipositor, which enables them to deposit their eggs in low lying plants and grasses, soil, bark, or dead wood. Most lay their eggs in clusters and have a sticky protective coating. The eating habits of the larvae depend on the species because some are carnivores like the adults but others are detrivores. Regardless, the larvae then overwinter and emerge as adults. The whole process ranges from 1-3 years!
Their chosen living space depends on the species but generally prefer habitats that are open, sunny, and dry. They prefer coming out during the brightest, hottest times of the day. They also like open or scattered vegetation, and some species even seek out bare ground.
Unfortunately, they are not very well studied and more research is needed to learn more about them. We do know that they occur everywhere but Antartica, they are voracious predators, and they prefer warm days and open vegetation for hunting. So far, there are over 7500 described species in about 556 genera. I hope one day to identify a robber fly down to species but that is still in the works!
Well, thank you for reading my blog. As always I hope you enjoyed this post as much as I enjoyed searching for the robber fly and putting this together. Until next time!
Yours,
Jade
