We interrupt this cool caterpillar...

Images of undisturbed subjects in their natural environment. All subject types.

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MarkSturtevant
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Joined: Sat Nov 21, 2015 6:52 pm
Location: Michigan, U.S.A.
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We interrupt this cool caterpillar...

Post by MarkSturtevant »

... because there are Phalangids mating.

In my favorite park, which is near Flint, Michigan, there is a massive stone and timber bridge that crosses the Flint river. Adjacent to this bridge and the river is a shady glen that has gifted me with many Special Finds. It was here that I photographed my first mantidfly, and also a Pelicinid wasp. Both are among the strangest of all insects. Each summer, this area also seems a favorite territory for the awesome dragonhunter dragonfly. So I always enter this glen with the view that here are some definite ... possibilities.
One day last summer I was just starting to explore the glen when I noticed a strange, symmetrical shape under one of the leaves of a redbud tree next to the river. Moving closer, I was very excited to see that it was one of the larger species of slug caterpillars that is shown in the first pictures. This is the spiny oak slug caterpillar (Euclea delphinii). Slug caterpillars do not have well defined legs, so they crawl slowly with peristaltic waves under the body. This species clearly has poisonous spines. The bright colors advertise that it is not to be messed with.
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I had plucked off the leaf that it was on to take the above pictures of the caterpillar, but the process proved to be challenging in the full sun. So I carried it to the shade and found a large, fallen tree log. Perfect for sitting. But just then there was a Phalangid (a.k.a. harvestman) trundling across the log, and I was just thinking that I should wait for it to make its way across when a second, leaner-looking Phalangid rushed out and tackled the first one! ??? They rolled around briefly in a blur of tangled legs before settling out, facing each other in a close embrace. This was an attempt at mating! I have never seen the entire process in these arthropods, so I put down the leaf and got to work taking pictures of Phalangids mating.

We interrupt the interruption of the caterpillar pictures to show a handsome male Phalangid of the same species. The long, curvy pedipalps are used in a rather specific way to clasp the female during mating.
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As shown in the next several pictures, after clasping the female the male (on the right) protrudes something weird. I suppose there is sperm transfer going on somehow. A Raynox 150 was put on the macro lens to boost magnification in the later pictures. The species looks to be Leiobunum vittatum, and you can see the female has a parasitic mite on her bum.
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After several minutes, the pair went their separate ways and I could claim the log for more caterpillar pictures. The slug caterpillar was of course carefully returned to its tree when I had finished with it.
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Mark Sturtevant
Dept. of Still Waters

Troels
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Joined: Mon Feb 15, 2016 11:06 am
Location: Denmark, Engesvang
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Post by Troels »

Spectacular and interesting!
Troels Holm, biologist (retired), environmentalist, amateur photographer.
Visit my Flickr albums

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