Snow spiders

Earlier this week, on a mild afternoon, I was working on my computer while Dan had taken Raven out for some exercise. I was startled by a sharp rap on my window. When I peered out, Dan was gesturing for me to come down: he’d found something he thought I might be interested in.

It turned out to be a spider, curled up on the surface of the snow. It was less than a centimetre long with all its legs tucked in to its body, and how he spotted it I don’t know. It was out in the middle of the milkweed fields, so I can only presume that it came out of one of the milkweed pods, or maybe up through a hole in the snow at the base of one of the stems. It would have been a long way for it to walk from other potential origins.

I started out trying to ID it by going to BugGuide.net and doing a search for “snow spider”. And lo and behold, there it was! Along with quite a number of other spiders on snow. I’m fairly certain this is a Ground Spider, family Gnaphosidae, maybe in the genus Gnaphosa, and could possibly be G. parvula. I make this identification based on the dimples/pale spots in the slightly-flattened top of the abdomen (others I looked at had rounder abdomens and/or lacked dimples). Another possibility that occurs in our area is G. muscorum, except that’s supposed to have a pale patch at the front/top of the abdomen. Really, though, I’m waiting for its identification by an expert at BugGuide.

In the meantime, while looking up whether Gnaphosa sp. are even active in the winter, I found this pdf article called the Phenology of Winter-active Spiders. The opening sentence states that there are 54 species of winter-active spiders in southern central Canada (the author was from Manitoba) and the article discusses the life cycle of each. The only Gnaphosa he mentions is G. muscorum, and all of his specimens for the species were collected in May-June-July (though all the species in his report are ones that are supposed to be active in the winter). So I may have to wait for an ID on BugGuide.

I ran off a few photos of Dan’s spider, then started walking back to the house. As I returned, I kept an eye on the ground, to see if any other critters might pop up (recalling also the caterpillar from a few weeks ago). No caterpillars, but I did find a second spider. Assuming it was the same as the first, I just ran off a few shots with the idea of posting one on the blog, following the first and saying “hey look, I found another.” When I got the photos uploaded onto my computer and looked at the spiders at about 20 times life size, I became pretty certain that they weren’t the same species. Their cephalothoraxes (the heads) weren’t the same shape, for one thing. The second one’s legs were thinner than the first’s. Hmm…

Looking more closely at my selection of “snow spider” results, I spotted this species in there as well. This is a Thin-legged Wolf Spider, belonging to the genus Pardosa. There are two genera that look very similar, and can be told apart by the presence or absence of a dark V on the cephalothorax. It’s absent on this one, therefore it’s Pardosa. The pdf mentioned above also had two Pardosa species listed. Neither of them were encountered in the winter, either.

This spider wasn’t found out on the snow, it came in on a piece of firewood. Dan also found this one and called me downstairs to see if I was interested. It’d probably been quite happily tucked away in the stacks of firewood in the garden “shed”. Very long-legged and delicate-looking, this is a Long-bodied Cellar Spider, Pholcus phalangioides, and is one of the most common household spiders. Originally native to the tropics, it’s now found in much of the world. It’s often one of the most abundant in any given house (or cellar, or woodshed). They build webs, and when disturbed will shake their web violently in an attempt to startle or confuse predators.

Their long-legged nature really only confuses them with one other type of arachnid, the harvestman, frequently called “daddy-long-legs”, although it turns out that both of these arachnids are sometimes known by that latter name. The specific name of the cellar spider, phalangioides, originates from the roots Phalangium (the genus containing harvestmen) and “-oides” which is Greek for “similar to” or “resembling”.

Cellar spiders are great for pest control. In particular, they will prey on other spiders, often species that are much bigger than they are. I found one comment on BugGuide suggesting that this would be a useful thing for folks living in Arizona and other places where venomous spiders may be a consideration. Encourage the cellar spiders to set up shop and it’ll help keep your other spider populations down! When food is scarce, they’ll turn cannibalistic, feeding on others of their species.

Here’s a neat series of shots submitted to BugGuide, of a cellar spider and its prey, which the photographer unwrapped and cleaned to see what it was.

Author: Seabrooke

Author of Peterson Field Guide to Moths. #WriteOnCon Mastermind. Writer of action/thriller SF/F YA. Story junkie. Nature nut. Tea addict. Mother. Finding happiness in the little things. Twitter: @SeabrookeN / @SeabrookeLeckie View all posts by Seabrooke