assassin bugs

Bug Hunters: Insects That Hunt Insects

Wheel bug stalking a Japanese beetle.  Image by Jody Thompson.

Wheel bug stalking a Japanese beetle. Image by Jody Thompson.

There's an incredible number of insects in the world. From nearly a million described species to an unimaginable number of individuals, nearly every biological role is covered. One of those roles is the predator.

Some people react to insects as if they're all predators, and we are prey. We can say though, unequivocally and logically, that people are never prey to insects, because we're just too damn big. Although, people often react like prey when they flip out over a butterfly and nearly break a leg to get away from it. Yes, I said butterfly - I’ve seen it happen.

Let's look at one of these predator such as the wheel bug (Arilus cristatus) seen in the image above. It looks tough as hell, like it's dressed in post-apocalyptic armor with a spiked wheel on its back, thick beak and stout body. Even their taxonomic family (Reduviidae) has a badass common name - the assassin bugs! I watched this wheel bug sneak up on a Japanese beetle (Popillia japonica) and slowly hover over it for a moment before instantly snatching it off the leaf. Japanese beetles are not fast or skittish, so it had no chance against the wheel bug.

Wheel bug feeding on a Japanese beetle.  Image by Jody Thompson .

Wheel bug feeding on a Japanese beetle. Image by Jody Thompson.

So, what's the benefit to you? Wheel bugs and other assassin bugs are just one part of the enormous ecological machine around us. These and many other insect groups keep parts of the insect world under control. When you get too many of one type of critter, their preferred food supplies change, diseases may run wild or there can be large-scale die offs. This happens at all levels of the animal kingdom, including the fuzzy and cuddly ones many prefer. These insect help keep insect populations more stable, which helps the entire system run smoother.

However, many people believe that what goes on in the world of these tiny bugs doesn't really affect their lives. Remember though that our food supplies and serious human diseases are tied directly to the insect world. Insects affect Christmas tree farms, become household pests, affect water quality, are food for birds and mammals everywhere and even affect the health of plant life across the world. These things can be very hard to wrap our heads around, but we only ever see the tiniest fraction of what's going on.

So, the message is that insects like wheel bugs, dragonflies, predatory beetles and many others help keep our world more stable. It's certainly much more complex than I've described, but sudden, large-scale changes in any part of the natural world usually affect us as well. Wheel bugs may have their hands full with invasive pests like Japanese beetles, but they and many other beneficial insects are working for us behind the scenes in many ways.