They’re harmless, let’s kill them

This article leads with a photo of a spectacularly beautiful joro spider.

Beautiful. I’d love to see more, but I am content with our native Argiope, we don’t need to import invasive species.

The title of the article, though, is this troubling claim.

Studies show Joro spiders are easy to kill and virtually harmless

That’s a disturbing juxtaposition: Harmless! and Easy to Kill!

Well, great. If they’re harmless, leave them alone, you don’t need to kill them. They tested how to kill them, anyway.

Coyle and a team of co-authors from Clemson, Southern Adventist University and Union College tested various products, some of which are labeled as spider killing products, while others came from scouring the internet to see what people were telling others to use, such as water, isopropyl alcohol, foaming dishwashing detergent, window cleaners, bleach, hair spray, vinegar and WD-40.

Those labeled as insecticides were effective in killing the spiders. Coyle said that while some household products did kill the Joro spiders, he would not recommend using them.

“They are not labeled as insecticides, therefore it is illegal to use them as such,” Coyle said. “Beyond that, it is not safe, both from a personal standpoint, or ecologically. It’s not good to be spraying machine lubricant or some household cleaner all over where your dog or child might be playing. We strongly encourage people if they must use an insecticide, use a labeled, legitimate one.”

Aaaargh. I would not be able to carry out a study like that — collect healthy animals, and ask students to kill them with random products from the garage and kitchen? It’s not ethical, and also, we already know the answer: our homes are full of industrial glop that can kill animals. I also don’t need to test whether dropping a big rock on a bug would kill it. I also wouldn’t do the study and then recommend that you use a commercially available insect neurotoxin to hose down a place where your dog and child might play.

I also wouldn’t be able to do the other part of the study.

For the second part of the study, the researchers forced the spiders to bite volunteers, who then ranked the pain based on the Wong-Baker FACES Pain Rating Scales, a pain assessment used in pediatrician offices where six faces ranging from a neutral expression (no pain) to a crying face (worst pain) are used to identify the pain level.

“We asked participants their pain level at several time points,” Coyle said. “It was never more than a 4 for anyone. Most were in the 1 range, which would be similar to a mosquito bite to most people. We also measured redness around the bite. Our conclusion was that Joro spider bites don’t do much and it doesn’t hurt most people.

I already have enough trouble recruiting research students.

But OK, the studies have been done, time to stop torturing spiders. Leave them alone.

A grim ending

We have a home Pholcus phalangioides living under our kitchen cupboard, who occasionally emerges when they’ve caught something in their cobweb. In this case, a ladybug, who has been trapped under there for the past day.

The spider is clearly fang deep in a gap under the beetle’s armor, but what adds a frisson of horror to the scene is that the beetle was still alive, it’s mouthparts and forelimbs slowly writhing as Mlle. Pholcus sups on her fluids.

The silence of the worms

I’ve been experimenting with feeding regimens for the spiders. What I’ve been doing is feeding twice a week with an excess of fruit flies until I feel like they’re big enough for mealworms. My feelings about their readiness for larger food are not reliable, and lately I’ve been seeing that these spiders are eager to hunt big game. Maybe I’ve been underestimating them.

So I lined up 15 containers with juvenile black widows, ranging from little guys about 5mm long to roughly twice that, and put a mealworm in each one. Then I left them alone, going to a meeting for an hour. I came back to a horrible sight.

Mealworms are like the cows or sheep of the invertebrate feedstock. They are quiet grazers that eat our vegetable scraps and don’t move very fast. I came back to all these containers of frantic, squirming, wiggling worms, they were writhing, flailing as if in agony. The spiders, even the smallest, were darting in to deliver small bites. A full grown spider would inject enough venom to kill quickly, within minutes, but these little fellows required multiple attacks to get a slow kill. It was ugly, and I felt sorry for the worms.

I came back the next day. All of them were dead, but in various states of digestion, from drained to blackening. My little carnivores are fierce and ruthless.

I’m going to have to change up my feeding schedule, switching from Drosophila, which are apparently little more than quick snacks to them, to mealworms as soon as they’ve got fangs big enough to puncture the cuticle. I should be able to cut back feeding from twice a week to once a week. I’ll just have to swallow my guilt.

If you were wondering how big these juveniles are…

They are quite small. Here’s one stroking Abraham Lincoln’s cheek.

You can also see the juvenile coloration — the adults wil be solid black, with just a red mark on the ventral abdomen. One thing I noticed was that when I put them in a container with a jumble of moss, they practically disappear, even with the bright red markings. More than once I transferred a spider to a new container and lost it, and had to poke around to be sure I hadn’t accidentally set it free on the lab bench.