Harvestmen

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Vonones sp., an ornate harvestman (Eatonton, Georgia)

There are some groups of animals that I don’t really pay too much attention to until a really striking member of their lineage presents itself. The order opiliones is one of those groups. Known colloquially as “daddy-long-legs” or harvestmen, these strange little arachnids are neither spiders nor venomous (they are actually more closely related to scorpions). They are quite innocuous creatures actually, more inclined to drop one of their hair-thin legs and run away than attack anything. Most typical species, including the common north american genus Leiobunum, are seemingly just one-segmented bodies with 8 long legs. I come across them frequently in my outings and usually either pay them no mind or simply stop for a moment to observe before moving on. There are some species, though, that are much more bizarre-looking. This year I have come across two of them, and now I’ve started to pay a bit more attention to harvestmen.

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A typical-looking harvestman, Leiobunum sp. (Kennebunk, Maine)

While in Georgia in March, I ran across several individuals of Vonones, a rather distinctive group of squat little harvestmen. These animals like to hang out under logs and other debris, and also fluoresce under UV light. When disturbed, they emit quinones (2,3-dimethyl-1,4-benzoquinone and 2,3,5-trimethyl-1,4-benzoquinone) from defensive glands and brush the chemicals on their attacker with the tips of their forelegs. These are certainly not the typical harvestman, so much so that some hobbyists keep them as communal pets.

A few weeks ago, while searching under logs on the Cornell Campus in Ithaca, I came across a single individual of an even stranger looking harvestman. Trogulus tricarinatus looks more like a large mite or perhaps a ricinuleid (dinospider) than the regular gangly harvestman I usually see around here. This was one I had been on the lookout for, since the few photos of the species on BugGuide are from the Cornell Campus and two localities in Massachusetts. This species is a European introduction, first recorded in the U.S. in 1962. It appears to be established in several parts of New York and Massachusetts but I could not find any information on whether it is spreading or whether it is having any impact on native species. An interesting question to look into, perhaps.

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Trogulus tricarinatus (Ithaca, New York)

References:

Banks, N. (1893). The Phalangida Mecostethi of the United States. Transactions of the American Entomological Society (1890-), 20(2), 149-152. Retrieved from http://www.jstor.org/stable/25076605

Eisner, T., Kluge, A. F., Carrel, J. E., & Meinwald, J. (1971). Defense of phalangid: liquid repellent administered by leg dabbing. Science, 173(3997), 650-652.

Muchmore, W. B. (1963). Two European arachnids new to the United States. Ent. News, 74(8), 208-210.

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