Night moves

Our spiders are very quiet during the day, but we noticed that every morning their cages were full of fresh cobwebs. We knew they were sneaking around at night, and we resolved to catch them at it. A student, Ade Atolani, and I put together a gadget so we could watch.

We got a Raspberry Pi with a NoIR camera, drilled a hole in a plastic cage, and mounted it above a spider. I had no idea if this would work adequately at all — would we have enough resolution to even see the spider? How effective was this camera at seeing in the dark anyway? — so we just slapped together a quick trial run. We turned everything on late one afternoon, told the Raspberry Pi to take a picture every 60 seconds, and let’s see what we get. Miraculously, it all worked, first try.

What you’ll see in the video is a rectangular wooden frame in a cage, and we’re looking down on it. There’s a nice velvety dark cloth on the bottom, to minimize glare and reflections. At the beginning, there’s diffuse light from the window, so the infrared camera isn’t kicking in yet, but when it gets dark enough, the IR lamps automatically switch on, and the purplish black cloth looks pink. The important thing is that we can see the spider all night long, as it goes through bursts of activity. Awesome.

It looks like we’re going to have to sample at a higher rate, because the behavior is very bursty. We’ll enclose the whole set up in a light-proof box to get rid of the extraneous light. I also want to try some side illumination with an IR lamp to see if we can resolve the webbing as it goes up. This was just a pilot experiment, but it’s very promising.

Good morning, babies!

It’s time to get an apartment of your own!

On the left in this vial you can see the egg sac; on the right the black shriveled thing is a mealworm that was consumed by Mom. Mom has been moved out already. All those little black dots everywhere? Baby spiders. I’m going to have to go remove that foam plug now, and quickly sort ’em all out.

Looking for Argiope in West Central Minnesota

Sorry, but I didn’t include the photos here, which are all closeups of great big hairy spiders with bold coloring. The complete illustrated story is on Patreon, and the photos are on two posts on Instagram.

Mary and I went on a little spider hunting loop yesterday, looking for Argiope. We took a southeastern route, heading off to Swift county, then detouring a bit south to clip through Chippewa county, then due east to Kandiyohi, and finally north and back west through Pope county to home. Our strategy was simple: drive through farm country on state and county roads, keeping an eye on the ditches that parallel all roads around here. When we saw lots of grass and brush filling the ditch, and when there was a safe place to pull over in the car, we’d stop and stroll about, looking for webs.

We really needed an “I Brake for Spiders” bumper sticker, because we were probably annoyingly slow. Good thing the roads were nearly empty!

One catch to this approach is that good grassy roadsides were scarce. Apparently, good Republican farmers have little to do and lots of tractors, so they trim everything. Have you ever seen a drainage ditch that looks like a manicured lawn? We did, everywhere. The best places had 1-2 meters of grass, where we’d walk in and be in the weeds to chest height or over our head. Actually, the best places were nature preserves and restored prairie.

We persevered, though, and found Argiope in every county we visited. They’re common, but they really don’t seem to like the kind of place where big bipedal mammals frequently bumble around. Living near people is OK, but they better not ever come over to visit.
So here’s one from Swift county:

Classic Argiope aurantia. Big, black and yellow, and a meter wide orb web with stabilimentum zig-sagging down the center.
Chippewa county is the emptiest place we visited, lacking any large towns and consisting of nothing but farms. They do have Argiope aurantia, though.

Kandiyohi county is kind of the inverse. It does contain one big town, Willmar, which was right in the way of our route, and Argiope does not like cities much. We finally found one as we were driving away by our usual expedient of pulling into farm access roads where the residents weren’t overzealous lawn fanatics.

We’d actually planned to hit up a couple more counties, but the weather turned grim, all gray and rainy. Even as I write this I’m listening to thunder. We’d decided to skip a northern loop of our drive and go home through Pope county, where we found Argiope trifasciata in a nature preserve.

One cool thing about this one is that there were two other webs in the same little patch, only a few centimeters away, and they were occupied by males, hopeful consorts I would guess.

We’re going to do it again next weekend, aiming for a western and northern loop, passing through Big Stone, Traverse, and Grant counties. Also on our list is another trip to the Ecostation in Ottertail county.

My mission for the day

I have received a mission request from iNaturalist. I have chosen to accept it. It did not self-destruct after I read it.

Records of Argiope aurantia (Yellow Garden Spider) and Argiope trifasciata (Banded Garden Spider) for 2020 started getting posted a couple of weeks ago. These two species are some of the most photographed spiders in Minnesota thanks to the female spider’s habit of sitting in her web in sunny locations like prairies and gardens. These species are easy to distinguish from one another and no other orb weavers match either their size or bold patterns.

Last fall the members of this project joined forces to find 13 new county records for Argiope aurantia and 12 new county records for Argiope trifasciata. But we still haven’t recorded these species in every county in Minnesota so I’m throwing down the gauntlet once again! Can we make these two species the first two spiders known from every one of Minnesota’s 87 counties?

The following 35 34 counties have no records of Argiope aurantia:
Aitkin, Beltrami, Big Stone, Carlton, Cass, Clearwater, Cook, Crow Wing, Grant, Houston, Hubbard, Itasca, Kanabec, Kittson, Koochiching, Lake, Lake of the Woods, Mahnomen, Marshall, Meeker, Mower, Murray, Nobles, Otter Tail, Pennington, Pine, Polk, Pope, Red Lake, Redwood, Roseau, St. Louis, Swift, Traverse, Wadena

The following 34 counties have no records of Argiope trifasciata:
Aitkin, Benton, Big Stone, Cass, Clearwater, Cook, Dodge, Fillmore, Freeborn, Goodhue, Hubbard, Itasca, Kanabec, Kandiyohi, Koochiching, Lake of the Woods, Mahnomen, Marshall, Martin, McLeod, Mille Lacs, Morrison, Murray, Norman, Pennington, Pope, Red Lake, Roseau, Sibley, Steele, Swift, Todd, Wadena, Wilkin

I’ll update this post as new county records get established. Happy spidering! (yeah, that’s a thing!)

You know what this means — ROAD TRIP! I noticed that West Central Minnesota counties are largely represented on the list. In my region, only Stevens (where UMM is), Douglas (where the larger city of Alexandria is), and Stearns (St Cloud) have had records for these species. Mary and I figure we can hit up 3 or 4 neighboring counties and make a small dent in that list today, and get out and explore at the same time. We might also squeeze in our local grocery run and have a picnic. We can’t lose!

We made a trial run last night, just here in Stevens county. We found lots of Argiope just in the grassy ditches that run alongside the highways around here, so this ought to be easy. If any of my fellow Minnesotans in more distant counties want to join in, please do.

If you don’t know what these spectacular spiders look like, I posted some photos on Patreon and Instagram.

Antici…pation

All baby spiders are now accounted for, but I may not be done yet. There are two more egg sacs awaiting the emergence of more hordes of spiders in the lab, and the only thing that might be sparing me right now is the temperature. The science building is at 18°C right now, which is cruel and wasteful, but it’s been that way all summer, I don’t know why. I have to go home now to thaw out — my fingers are just frigid. The rest of me is OK, because this is how I dress in the lab now, in August.

It’s nice to have an excuse to wear my spider sweater in the summer, but still…

Also the hat is necessary to control my pandemic hair, so I can’t blame that on the physical plant.

Wait, you didn’t want to see a picture of me, you wanted to see a sexy photo of a mama spider and her great big egg sac? OK, I put it on Patreon and Instagram. Trust me, the spider is beautiful and maternal, despite having to deal with an unusually chilly environment.

Spider Math

I have spent many hours today, counting spiders. I’m trying to keep track meticulously to figure out where the danger zone in spider raising is, and I don’t think I’ve reached it yet. I’m dealing with 3 clutches of spiders from 3 different mothers and 3 different fathers (they were caught in relatively different locations), and I’m simply tracking numbers right now.

Runestone line, 16 days old: 22 spiders, 96% survival, density of 1.1/vial.

Horticulture line, 15 days old: 94 spiders, 90% survival, density of 2.2/vial.

Myers line, 14 days old: 71 spiders, 93% survival, density of 3.0/vial.

There’s an accidental experiment in there. The first hatching from the R line was small and manageable, we were able to quickly and efficiently move them into vials, no sweat. They’re mostly living as single spiders in each vial.

The H line, on the other hand, just erupted with lots of spiderlings and we were a little overwhelmed and rushed. A fair number simply escaped, some we just gave up on and left in the cage with their mothers, and we were straining to get them all contained…so we had on average 2 per vial, and the max was 5 in a single vial.

The M line also taxed us, because I ran out of racks to store all these tubes. We tried to get as many as we could into the available slots, so there you go, on average 3 spiders per vial. I could at least look and see if the density in the first few weeks of mobility made a difference in survival.

And no, it doesn’t seem to. In fact, most of the deaths were in vials with single spiders, which makes me wonder if there might be some cooperative work in bringing down fruit flies, which are much bigger than the spiderlings. I did see, though, that big size disparities are emerging — some individuals were twice the size of their siblings in the same vial. I haven’t seen any sign of cannibalism yet, but that may arise if I don’t keep everyone well fed. Which reminds me, I’ve got 187 spiders down in the lab waiting for dinner.

The spider struggle continues

13 days until classes begin, and this last batch of spiders are now about 13 days old. I took a few pictures (I stashed one on Patreon and Instagram) and had to struggle a bit with the photomicrography system, which I’ve mostly neglected this summer, on top of struggling with putting a lab demo together on video. Tomorrow is going to be busy feeding a few hundred spiders…well, maybe. Another thing I’ve noticed is that some of the babies have died, just out of natural mortality, I think, and tomorrow will involve counting the living and the dead, hoping the former outnumbers the latter.

Somewhere in here I’ve got to get my syllabi order, too.