Rediscovered

pearl crescent on spearmint flowers
While skimming through images in my folders, I came across this pair taken back in 2012, and decided to feature them to appease all of the people who started coming here because of the bugs, who now have nothing to see during the cold months. You haven’t been forgotten.

On the spearmint flowers this butterfly, likely a pearl crescent (Phyciodes tharos,) was holding a little too still – they might often pause and sun themselves, occasionally fanning their wings slowly, but won’t typically allow this close an approach. Not to mention that the wings aren’t held in a natural position. The faintest clue can be seen to the left of the butterfly if you look close, but the real explanation came from lying on the ground below and shooting up from underneath – this next image still sparks the memory of a damp shoulder obtained from not using a ground pad when I got the shot.

white-banded crab spider captures pearl crescentIt will probably help if I explain what you’re seeing here, since it’s an odd angle and much is obscured. The most noticeable aspect is the pale, dimpled abdomen of a crab spider, most likely a white-banded crab spider (Misumenoides formosipes) – its cephalothorax (head) is partially hidden behind the butterfly it is gripping. You’re seeing the butterfly tail-first from below, the abdomen out-of-focus in the center of the shot since I was after the spider; one wing goes into the top right corner, the other down the left side. Not the best illustrative angle, which may be why I never bothered to feature the images back when I got them, but there’s a real limit in many situations. The spearmint plants were not very tall, and to get a perspective that showed the spider at all required shooting almost straight up from flat on the ground, with no opportunities for other angles. The lighting is deceiving, since it comes solely from the flash – in ambient sunlight this would have been in deep shadow. Trying for anything else might have resulted in disturbing the subjects, which could have made the spider discard its meal and scamper for cover.

The spider probably has a grip on the thin neck of the butterfly; this seems to be a very common trait of spiders, likely because it provides the best access to internal fluids. Arthropods don’t really have blood vessels, but instead an open circulatory system – this means the ‘blood’ (actually hemolymph) runs freely throughout the body cavity. Yet there are still organs that ensure that the hemolymph reaches the head, and it might well be this that the spiders tap into; it could also be that their venom works most effectively when applied here, eradicating struggling quickly. I’m not an entomologist, so this is only speculation, but the grip in this area is something I’ve seen dozens of times.

Another example is provided by the same species of spider from this past summer, an image I dug out while writing this post – yes, they can change their coloration to match the flowers they conceal themselves within.
white-banded crab spider with bumblebee
Unless it’s very early morning after a chilly night, bumblebees never hold still, and certainly not in this position, so it was a dead giveaway that something else was happening. At least, it is to anyone who takes a moment to think about insect behavior – this was in the NC Botanical Garden, and plenty of people were walking past and paying no attention to this tableau at all, though some of them might have been there for the flowers and not the bugs. I know, right? There’s no accounting for taste…

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