Technically this photograph of Labidomera clivicollis (swamp milkweed leaf beetle) doesn’t qualify as a “one-shot”, as I did take a few other shots as well. However, this was the only shot out of the handful that I didn’t throw away. It’s not perfect—the right front and left rear legs are raised awkwardly, and the lighting is a bit harsh. However, the important parts of the beetle are in focus, the composition is acceptable (with all parts of the beetle within the frame), and there is pleasing value contrast between the orange and black body of the beetle, the green plant on which it sits, and the clear blue sky in the background. The plant’s flowers have even added a smidgen of pink. All of the other photos lacked either focus or composition, neither of which are easily “fixable” in post-processing. The difficulty in getting a better photo is a result of the beetle’s refusal to settle down and stop walking and my lack of desire to spend an inordinate amount of time waiting for this to happen as opposed to finding the insect I was really looking for (more on that in a future post).
I found this beetle on swamp milkweed (Asclepias incarnata) in Hickman Co., Kentucky. As the common name suggests, swamp milkweed is one of the main hosts for this rather large beetle (at least, by leaf beetle standards). However, they can and do feed and develop on other milkweeds, especially common milkweed (A. syriaca), and even related genera such as swallow-wort (Cynanchum) and twinevine (Funastrum) (all belonging the family Asclepiadaceae).
Labidomera clivicollis is part of the orange and black milkweed mimicry complex, which includes monarch butterfly (Danaus plexippus), red milkweed beetles (Tetraopes spp.), large milkweed bug (Oncopeltus fasciatus), small milkweed bug (Lygaeus kalmii), milkweed assassin bug (Zelus longipes), and others. Most of these insects have evolved mechanisms for avoiding or detoxifying cardenolides (produced by milkweed as a defense against herbivores) and sequestering them within their bodies for their own defense against predators. This represents a classic example of a Müllerian mimicry ring, in which multiple insect species—sometimes from different families and even different orders—share a common warning color. Predators learn to avoid these colors and, thus, avoid all of the species within the mimicry ring.
© Ted C. MacRae 2014