On May 16th, 2015 I participated in my third Glen Echo Bioblitz. (I know I am running a little behind keeping my blog updated.) The Glen Echo ravine is located in the Clintonville area of Columbus, Ohio. Although it is surrounded by a matrix of urbanization, it is a nice little wildlife refuge. We found many interesting things, including several that had not been noted in previous years.
One of the spider families that I think is often overlooked is Segestriidae, commonly called tube web spiders. These spiders only have six eyes (they lack anterior median eyes) and have paired tracheal spiracles next to the book lungs. The construct a silken tube retreat, often in decaying wood or amongst debris, (Bradley et al. 2013) that has a few “trip lines” radiating from the opening. They spend their time in the tube waiting for something to trigger one of those trip lines. When in their tube they are unique in resting with three pairs of legs pointed anteriorly, and only one pair of legs positioned posteriorly (Bradley et al. 2013). Ariadna bicolor is the only species of Segestriidae found in our area.
Not everything that looks like an ant is an ant. Synemosyna formica is a jumping spider (Salticidae) that mimics ants in its appearance. Their mimicry is so convincing that Dr. Rich Bradley conveyed in his book that an entomologist he knew once found one pinned in an ant collection (Bradley et al. 2013). Like most jumping spiders this is an active hunter, chasing down its prey and pouncing on it.
Hentzia mitrata is a very handsome spider, well at least in my opinion. The males have enlarged front legs that are covered in white setae, which is a beautiful contrast to the golden coloration of the top of its carapace and abdomen. I had read about the fact that the males raises his legs as part of the courtship dance he performs for the female (Bradley) and was surprised to see two males interacting. You can watch the video here. I apologize that the video is not the best quality, but the habitat near where the spiders were interacting posed a challenge to me getting close enough without disturbing them. If you look closely at the start of the video you will see a female (top center) move to the underside of a leaf. It appears that the males are comparing leg length, maybe in a fight for dominance of the area, or as a way to impress the on looking female.
I have stated before that many spiders cannot be identified by a photo alone, and many are too small to even make a good educated guess on identification in the field. It is not uncommon for me to return from a bioblitz with vials of spiders. If I can I try to identify them by placing the live spider under my microscope and photographing the important features. One that I was successful in this with was Thymoites unimaculatus. These are small Theridiidae (cobweb spiders), maybe 2mm in total body length, so can be easily missed. Luckily this female positioned herself such that I could get a reasonable photo of the epigynum for identification.
There were numerous Pardosa sp. (Lycosidae: wolf spiders) throughout the ravine. Lycosidae males are also known to dance for the females, and I often see the males drumming their pedipalps on the substrate. One of the ways to tell that a spider is male is the “boxing gloves” he seems to have on his pedipalps. I thought this little Pardosa male looked more like he was wearing mittens! You can watch a very short video of his display here. (Also look carefully and you can just see the rear legs of the female that was ignoring him!)
I was invited to the bioblitz as a spider expert, but I try to be on the lookout for other interesting critters as well. There were lots of interesting things, but I will highlight just a couple.
We were privileged enough to have an Amphion floridensis (Nessus Sphinx moth) pay a visit to out bioblitz. This is a large (3.7-5.5 cm) day flying moth and can be identified by the prominent yellow stripe on the abdomen (Horn and Ohio Division of Wildlife 2014). I find them to be beautiful and captivating to watch. Their larvae feed on grape and Virginia creeper (Eaton and Kaufman 2006). The Ohio Division of Wildlife has put together a nice field guide to the moths of Ohio that you can access online.
Lastly, I wanted to share an unusual beetle that made an appearance. Arrhenodes minutus (The Oak Timberworm) These are “primitive” weevils of the subfamily Brentinae. There are only 4 species in this family found in the US, and 3 of those only occur in Florida. Arrhenodes minutus ranges from Florida to Canada, and the larvae are known to feed on oaks (Eaton and Kauffman 2006). The females lay their eggs on exposed wood of living trees and the young can take up to four years to mature (Buchanan 1960). They are sexually dimorphic; the females have a long “beak” that they use for excavating a hole for their eggs, whereas the males have a pair of “pincer like” jaws (Milne and Milne, 1980). Therefore we know that this was a male, he was willing to pose for several photos before taking flight.
It is always fun to participate in a Bioblitz. Not only is it fun to go out and chase down critters to add to the list, but it is a great opportunity to interact with the public and raise awareness of the animals and plants that seek refuge in areas like Glen Echo. There are amazing things in your neighborhood too, if you just go looking for them.
Bradley, Richard Alan., Buchanan, Steve., American Arachnological Society.,. 2013. Common Spiders of North America. University of California Press, Berkeley.
Buchanan, W. D.,. “Biology of the oak timberworm, Arrhenodes minutus.” Journal of Economic Entomology 53.4 (1960): 510-513.
Eaton, Eric R., Kaufman, Kenn.,. 2007. Kaufman Field Guide to Insects of North America. Houghton Mifflin Co., New York, N.Y.
Horn, David J., Ohio Division of Wildlife.,. 2014. Moths of Ohio: Field guide. Publication 5467 (0214) http://wildlife.ohiodnr.gov/portals/wildlife/pdfs/publications/id%20guides/pub5467.pdf
Milne, L. J., Milne, M. J. G.,. 1980. The Audubon Society field guide to North American insects and spiders. Knopf: distributed by Random House, New York
Spiders and More 