It’s Arachtober so I wanted to share, in case you didn’t already know, that the University of Richmond’s mascot is a spider (named WebstUR, I gather). That’s pretty cool. Not as cool as the Evergreen State Geoduck, but nonetheless pretty notable for a nation that tends to hate spiders.
But because Arachtober is about arachnid awareness, I’d like to point out that the logo the school uses is almost certainly a mite, not a spider. I’m sure I’m not the only one to notice this. The main reason it looks like a mite is that it lacks a cephalothorax (head plus thorax), something that all spiders have. Also, their mascot has legs that don’t have clear segments. iNaturalist, a website that uses an AI to recognize and identify organisms, also thinks the logo is a mite (or tick):
Given the shape of the idiosoma (body) and size of the pedipalps, I’m wondering whether the artist might have based his or her drawing on a tropical fowl mite (Ornithonyssus bursa) or something related. Below is a drawing of one of those, though the legs don’t look quite long enough to match the logo exactly.
If you have any details on how the University happened to base its logo on a mite, I’d love to hear from you.
During a run this week I passed an abandoned, 30-gallon aquarium with easily 10,000 larvae doing their thing (wriggling). I came back later, took some photographs (on my Instagram soon if you’re into that), and then dumped it, sending the larvae to their deaths but also releasing a cloud of perhaps 100 newly-eclosed adults. I suspect the aquarium had been there for years, pumping Asian tiger mosquitoes (Aedes albopictus) into the neighborhood. Given the aquarium’s location at the edge of busy parking lot I’m sure that thousands of people have looked at it and thought, “Huh. Looks like an abandoned aquarium full of dirty water. Next to a Christmas tree. I bet there’s a story there!”, and then moved on with their lives.
In case you are unsure what an infestation looks like, the next two photographs show what the adults, larvae, and eggs look like. Asian tiger mosquitoes lay eggs singly on the sides of containers or on moist objects floating on the water. They can last over a year as an egg, waiting for conditions to be just right.
Here’s a sample of the water I pulled from the tank.
But not all the eggs were Aedes albopictus (there are 60 species in PA alone). Here’s a raft of eggs in the aquarium from a different species (Culex sp.). The raft is lodged on a leaf but normally it just floats around until the larvae pop out. Anopheles (another common genus) has eggs that are deposited singly but float with the help of cute little life preservers.
But that’s not all! Yesterday I found a recycling bin behind a church with similar numbers of larvae. Given the amount of leaves decomposing in the bottom I suspect it has been like this for at least the whole summer. Again, it really is strange that nobody did anything about it. It’s right next to a sidewalk that gets lots of traffic (at least on Sundays) and is probably 10′ away from a playground at an infant/toddler daycare center. Poor kids. (I dumped it.)
Given how much people hate mosquitoes it left me thinking how the public outreach about mosquito control has failed on the most basic level. Everyone should know enough about mosquito biology to know how and where they breed, and everyone should feel empowered to do something. Being proactive is so much better than adopting what I think is the common view, “Well if the mosquitoes get bad enough I’m sure the government will spray insecticides from planes.”
All it would take would be a nicely worded message from a town official to mobilize residents into a mosquito watch. Something like, “If you see mosquito larvae swimming around in a container when you are out walking your dog, please turn the container upside down or alert the owner about it. Thanks.”
Last week when I was at Ridley Creek State Park I crossed paths with a tree tour led by wildlife biologist Gary Stolz (PA Dept of Conservation and Natural Resources). I promised the group that I’d post photographs of things I’d seen at the park. Here are the highlights:
Long-tailed giant ichneumon wasp
The largest and most colorful was clearly the long-tailed giant ichneumon wasp (Megarhyssa macrurus) that I found ovipositing into a red maple. Actually, there were perhaps a half-dozen of them, all presumably targeting the larvae of Tremex columba (a sawfly) that were busy eating the tree. The presence of the sawflies is given away from probably a mile away (I’m guessing here) due to the odor of the symbiotic fungus they use to help digest the wood. Once on the tree, though, the ichneumon probably locates a larva by sensing the vibrations it makes when chewing. The ovipositor is approximately 2″ long and is tipped with a cutting edge (as you might guess). It also drips out a fluid that helps dissolve the wood. An amazing insect to watch.
Green’s giant ichneumon wasp
Also on the same tree were several Green’s giant ichneumon wasps (Megarhyssa greenei). This species has a shorter ovipositor (among several other differences) but does pretty much the same thing as the species above.
Unknown wasp in Tribe Ephialtini
Also beautiful but much smaller (perhaps 12 mm), I found this wasp ovipositing into a nearby tree that was completely dead and covered with moss. I’m still working on an ID (it’s something in the Ephialtini). Which means, like many of the insects I photograph, I’m hoping that an expert will eventually help me identify it. Sometimes that process can years but I’ll update this page if there’s any movement. For those curious, I post photographs to iNaturalist and BugGuide for help. And I often ask my Dad (Foster Forbes Purrington), an entomologist.
The last wasp of the day is Coelichneumon navus, another ichneumonid but with a concealed ovipositor. This species has been known to parasitize fall webworm (Hyphantria cunea) and cypress looper moth (Iridopsis pergracilis), but like many of the 100,000 or so members of the family Ichneumonidae not much is known about its natural history. I found two caterpillars on this tree but haven’t yet ID’d them.
Another insect with no common name, Gnophomyia tristissima live, love, and die around rotting hardwood logs. These are crane flies and can be identified by their bright yellow halteres (remnants of their second pair of wings) and black bodies. This photograph shows mating but afterwards the male seems to guard the female while she oviposits (if you want to see that, click on image to be taken to a site that has additional photographs). I spent about 30 minutes watching and photographing them and could have stayed longer. But the mosquitoes were exsanguinating me.
American nursery web spider
Earlier on my walk I found a rather orange American nursery web spider (Pisaurina mira). It was also rather large.
Banded fishing spider?
I can usually narrow down spiders given their eye arrangement and details of web (or lack thereof), but this is stumping me. My tentative guess is that it’s a freshly-molted (teneral), juvenile banded fishing spider (Dolomedes vittatus). I’m trying to get this confirmed so check back if you’re curious. Astute readers will notice that it’s on a tree, not near water, but apparently there are few members of Dolomedes that can live away from water just fine. This is one of those species.
Northern water snake
This was the first time I’ve seen a northern water snake (Nerodia sipedon) but apparently they are super common. This one was perhaps 2 feet long but they get as big as 4 1/2 feet. Non-venomous, though, in case you were wondering.
I’m still working on an identification but my current guess is sulphur tufts (Hypholoma fasciculare). Or, if you prefer, sulfur tufts. I really enjoy photographing young mushrooms but the consequence is that they are harder to identify.
That’s it! If you have any questions, send me a note or leave a comment.