It’s an unboxing video! I hear those are popular. Only what I’m unboxing is a pair of spider egg cases.

Spoiler: I don’t find any spiderlings inside. I find evidence of them being there, in bits of molted cuticles, but nothing was moving. I’ll let them warm up for a few days and look again.

If you want to know more about how spiders overwinter, here’s a source:

Tanaka K (1997) Evolutionary Relationship between Diapause and Cold Hardiness in the House Spider, Achaearanea tepidariorum (Araneae: Theridiidae). Journal of Insect Physiology 43(3):271-274.

The relationship between diapause and cold hardiness of the house spider, Achaearanea tepidariorum, differed geographically. In a cool-temperate population, enhanced chilling tolerance and supercooling ability were observed in diapause individuals, whereas a subtropical population showed only chilling tolerance. Because this spider is considered to be of tropical origin, it would follow that the ancestral diapause of this spider was equipped with chilling tolerance, but not with an increased supercooling ability. It seems that the ability to lower the supercooling point evolved through natural selection in the course of expansion of this species to the northern climates.

Now I have an excuse to visit Florida on a collecting trip, to gather representatives of southern populations. Maybe I should go in, like, February.

One other thought I had about the barrenness of these egg cases: it’s like the Donner expedition. Maybe one of the ways spiderlings survive the long cold winter is by eating their siblings, and this winter was particularly harsh.

It’s been a while since I had anything new to report — the colony is just sitting there, waiting for me to provide the ladies with some males, since they ate all of them. But we’re gearing up for a field season, so there were a few things I was able to try.

I’ve written up a protocol for our summer spider survey. It’s mainly a series of steps we’re going to carry out as we scan a garage, because consistency is important. We’re not going to be able to see every spider in every place — they’re sneaky, quiet little buggers — so we need to survey each environment in the same way, so that we can compare the residences, even if we know we’re going to miss animals. So Mary and I put on headlamps, plunged into our frigid garage and went through the motions to see how practical my plan was.

We didn’t expect much. It’s been a hard winter, and while today felt much warmer and the snow is melting, it really is still only 2°C, hardly happy weather for spiders, and not any better for their prey. We went spider hunting anyway.

As expected, there wasn’t much alive out there, maybe. The only spiders we saw were cellar spiders, Pholcidae, and they didn’t seem to be up to much. In fact, they might have all been dead. They were all inert and unresponsive to touch, but were still strangely plump and life-like, if still. They could be little frozen corpsicles, or possibly estivating. We couldn’t tell. We counted them anyway, if they looked intact and like, maybe, they’re going to rise from the dead at some point. It was all practicing the protocol, anyway.

The end result is that our cold and unpleasant and rather cluttered garage, 5.3m wide and 6.1m deep, has walls that are all covered with cobwebs, especially any part of the wall that is more than just a bare surface. If there was so much as a nail sticking out of a sheet of fiberboard, there was a cobweb on it. We counted a total of 63 zombie pholcids in that little space, and also found 11 egg cases of at least 3 different types. We’re starting to think our biggest challenge will be counting all the spiders in a reasonable amount of time once summer arrives with the mosquito season and the happy little beasts start fornicating fiercely.

One neat little surprise: along a back wall, there’s an area with a rack of shallow shelves, and Mary excitedly tells me that she has discovered spiderlings! I was skeptical and thought that was metabolically improbable given the ambient temperatures, but when I looked, sure enough, there were sheets of webbing in all of those shelves, and in all of them there was an explosion of tiny white dots with itty-bitty hairlike protrusions. They were of the right size, and that was the kind of scattering I’ve seen in newly hatched spiders in the lab, but I couldn’t imagine they might have survived a Minnesota winter, and they didn’t.

I twirled a patch of cobweb with the putative spiderlings onto a brush, and brought it into the lab, and sure enough…spiderlings. Well, the molted cuticles of many adorable baby spiders. Here’s a photo.

[Read more…]

I was reading about Greta Binford, the spider-woman, and there’s a lot of good stuff here. I was a tiny bit put off by this bit, though:

Binford came late to the study of spiders, and without morbid predilections. She grew up on a small corn- and-soybean farm in west-central Indiana—“dull spider country,” she calls it.

I’m afraid Minnesota might be even duller spider country, and I’m a bit concerned about the lethality of our winters — it might be a very seasonal spider country. But that doesn’t make them less interesting. I’ve already got some ideas for experiments to test mechanisms our local populations have for coping. Also, even in winter I’m finding lots of spiders indoors, just not the species I was focusing on.

Binford is forgiven, though. She’s most interested in spider venoms, and that’s not a particular strength of upper midwestern spiders. I’m more into development and behavior, so there’s plenty to keep me occupied here.

But this bit rings true, for sure.

The key to good hunting, Binford said, was to have a “search image” in mind. Wolf spiders, for instance, can be found by their eye shine. When you train a flashlight beam over your back yard at night and see a faint glimmering in the grass, those might be spiders gazing back at you. Loxosceles tend to splay their legs like asterisks, and to gather in pockets of dampness—anything from the bottoms of rotting logs to the spaces behind steam pipes. “It reminds me of hunting for morels as a kid,” Binford said. “There’s a kind of Zen moment where everything falls away and there’s just you and the spider.”

The stairs led down to a long, open space, with pipes and wires hung low from the ceiling. Bits of graffiti flared into view, as our headlamps swung past, and strands of webbing caught at our faces. Most of it belonged to pholcids, or daddy longlegs, Binford assured me. Their venom is strong enough to kill a mouse, and they prey on other spiders, but their fangs are too small to hurt us. She played her beam along the bottom of a wall and held it on a Steatoda, a bulbous relative of the black widow, famous among arachnologists for turning radioactive and biting Peter Parker in the recent Spider-Man film. Then she stopped and scanned the room from end to end. “It’s like an Easter-egg hunt,” she said. The spiders were hiding in plain view.

I’ve experienced the same phenomenon! I’ve been walking these halls for years, totally oblivious to spiders, and now that I’ve started seeking them out, they’re everywhere! I find myself looking in corners, and window frames, and crevices, spotting cobwebs or fragments of chitin, and tracking down these little guys who share our homes and office buildings. If you’re an arachnophobe, I recommend not ever looking for them, or you’ll start spotting your nightmares all around you. Don’t develop that search image in the first place.

But don’t worry.

Spiders have a bad reputation, largely undeserved. The great majority aren’t venomous enough to harm us, or their fangs are too small, or their jaw muscles are too puny, or they simply see no profit in attacking large, indigestible creatures that can crush them with their toes. Unlike snake venom, which is designed to kill vertebrates, spider venom is almost always meant for insects. Its toxins can stop a hornet in mid-flight, but they lack proper targets in the human nervous system. “If we were wired for spider venoms the way insects are, we would be screwed,” Binford says.

She is studying Loxosceles laeta, a more potently venomous relative of the infamous brown recluse, which is infesting a Goodwill building in Los Angeles. I don’t know if you’ll find this part of the story reassuring.

When Binford milks laeta in her lab, their fangs yield about ten times as much venom as other Loxosceles’, and medical records suggest that their bites leave larger lesions. Yet, even if the Goodwill’s population spread across Los Angeles, it isn’t clear how much of a threat these spiders would pose. Laeta are easily as reclusive as their North American cousins. They keep to dark, quiet areas and shrink from human contact. When they do bite, the venom doesn’t always have an effect: some people’s immune systems aren’t sensitive to Loxosceles toxins. Five years ago in Lenexa, Kansas, a family of four trapped and killed more than two thousand recluses in their nineteenth-century farmhouse. Yet no one in the family suffered from a bite.

I would love to find a building with thousands of recluses lurking in it, but it’s not likely. They don’t seem to have taken to living this far north. But this might be one of the advantages of climate change, you never know.