At first glance they look like a collection of the same, very small dark insects with a red to brown head, orange thorax and an abdomen of white lines on black. But after further inspection, there are two distinct types of insect on the fence posts near Mount Pisgah’s main entrance, both of a similar size, with similar coloring, living in the same location. To see them together, click on the third link below.
Twice recently, I’ve seen these twinning species scurrying about near each other: the velvety tree ant, Liometopum occidentale, and a mirid plant bug with the scientific name Pamillia behrensii. It’s the bug that benefits from the mimicry.
Ants have an arsenal of defenses: They are notoriously bad tasting, have powerful jaws that can leave a mark or worse, and can deploy chemical weapons when they’re bothered. There are thousands of critters that have evolved to mimic ants in order to avoid predation, including bugs, beetles, flies, mantises, crickets, and even spiders. All of the pretenders live longer because they look like ants.
There is very little information about Pamillia behrensii. The studies I found about the little bug relate to its relationship with the velvety tree ant. It turns out the bug also secretes a chemical poison to repel its aggressors. A 2019 paper found that the bugs are harassed by the ants, but that they usually survive because of their chemical defenses. Interestingly, the chemical they secrete, benzoquinone, does not match the ants’ noxious spray.
The ants can reportedly be aggressive, and have a nasty bite, so don’t try collecting them by hand. They live in decaying wood and can be troublesome (like carpenter ants) if they set up in human-built structures. On the plus side, they’ve been spotted pollinating, and they drink honeydew from aphids, a behavior I caught on camera.
Stay curious!
See more of Karen’s work here.
Sources:
Academic paper on the bug’s chemical production: https://authors.library.caltech.edu/records/rrttz-dbp43. Accessed 1/2/24.
Academic paper on velvety tree ant colonies: https://escholarship.org/uc/item/0d26s1mt. Accessed 1/2/24.
BugGuide photos showing both species together: https://bugguide.net/node/view/1047083. Accessed 1/2/24.
