Leaf-footed Encounter

Top Photo: Leaf-footed bug encounter on path.

About one and a half weeks ago here on this blog, I mentioned an insect called a leaf-footed bug. I also posted a picture of the insect. At the time, I wasn’t sure of the identity of the insect beyond leaf-footed bug of which there are about 80 species in North America. Today, I came across two others of what appear to be the same species on the path in a closed (to the public) section of the outdoor area of the museum.

I believe the encounter, before I interrupted the bugs, was for mating purposes. The rendezvous was terminated when I came in too close and too fast with my camera and spooked the lead bug, who took off in a rapid retreat to the side of the path (rapid retreat for leaf-footed bugs that is, they don’t move very quickly). The second bug marched off after the lead bug. But, as is often the case, I was called away on other duties and wasn’t there to witness a resumption of their meeting if indeed they did resume their presumed coupling.

Male in hot pursuit of female.

As mentioned in my earlier post, the insects, leaf-footed bugs, are named for the flared processes on their hind legs, the tibia, which in some cases resemble leaves. Some leaf-footed bugs have flared tibia, some don’t. Those that do, have varying shapes and sizes of “leaf” according to species.

With this encounter on the pathway, I decided to try and nail down the ID of the creature. It took some searching, but I’m confident the insect is Acanthocephala declivis. I’ve come to this conclusion based on three different characteristics, the shape and size of the “leaf” on the insect’s hind tibia (the long middle segment of the hind leg), the shape and angle of the humeral angle (broad “shoulders”), and the two black spots or warts (tubercles) on the pronotum, just behind and above the head of the bug (see photos).

Arrows point to (top) humeral angle, (middle) femur, (bottom) tibia).
Tubercles on male bug.
Tubercles are easier to see on the female.

The differences between the Acanthocephala species which most closely resemble this one are almost obvious once you know what they are. Without going into details, here’s a link to at least one source I used to help with the ID (Review of Acanthocephala – Fort Hays State University).

The determination that the insect meeting was for mating purposes is based on the fact that the two insects are male and female. The bug in the rear (top photo and below) has thicker femora (the large, thick leg segments with spines between the tibia and body) than the bug in front, a characteristic of males. It appeared to me that the male was slowly and cautiously approaching the female from behind. And I believe, had I not interrupted, mating would have occurred.

Even with the out of focus female (top), the difference in size of the femora of the two insects is noticeable, more massive in male (bottom).

There’s always something new to discover.

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