What super-cool insect has some of the traits of a walking stick, a praying mantis, and a water strider but is none of those things? It’s this week’s star: The thread-legged bug.
I found this true bug on a railing near the Incense-cedar Exhibit. I had to stare at it for a while, under magnification, to understand what it was doing. Specifically, there wasn’t a piece of bark on the wood in front of the creature, it was its own long and folded front legs. This thread-legged bug (TLB), was resting in a downward-dog pose.
Emesinae subfamily bugs are also called thread-legged assassin bugs, which is a spoiler alert for the fact they eat insects, not plant matter. Their four filament-thin legs give them a special superpower: Because they walk so lightly, some TLBs stake-out spider webs and eat the prey caught in the web. Note of caution to the arachnids: TLB’s sometimes also eat spiders.
This bug’s front legs are thicker, and have pincers like a praying mantis. Those spines help capture prey, then the bug injects its relatively short but pointed rostrum into it.
When it walks, this species (Barce fraterna) holds its front legs forward and underneath its head. That’s right, it walks with four legs.
I took video and the gait pattern isn’t what you’d expect: It moves the back left leg, then the front left leg, then the back right leg, then the front right leg, and so on. The gait is a bit slow and deliberate, and from the top the insect looks like a stick bug. Some of the other genera of TLB’s look even more like stick bugs, because their abdomens are slender and not oval-shaped like this one.
Thread-legged bugs live in most of the U.S. states, and in regions all over the world. In fact, I came upon research about one species that was discovered thriving deep inside lava tubes in Hawaii. It has “greatly reduced eyes and no pigmentation whatsoever.”
Stay curious!
See more of Karen’s work here.
Sources:
Description of the Hawaiian tube-dwelling TLB: https://scholarspace.manoa.hawaii.edu/server/api/core/bitstreams/7202a6c7-ac5e-4739-9365-1540a9a710f8/content. Accessed 12/12/23.
Info from the University of Nebraska—Lincoln: https://entomology.unl.edu/scilit/Maggie Heumann Thread-Legged Bug.pdf. Accessed 12/12/23.
