Fortunately, I’m not as interested in social behavior of spiders as I am in just general development, physiology, and behavior of individual spiders. Here are some recent cool things I’ve read.

I’m working with Parasteatoda and Steatoda in the lab, so of course I’m curious about their venom. Maybe you wonder about what those common house spiders are packing, too. Here’s a breakdown.

What’s it all mean? A is showing us the number of genes involved, while B is indicating the expression levels of those genes. It looks like about a third of the genes are toxins, but that those are relatively highly expressed in the venom. The purples are not toxins, those are ordinary digestive enzymes. An important component of the venom is a collection of enzymes that break down proteins and fats and carbs, everything you need to turn guts into a nice soup. The oranges are the actual toxins — all the “latro” prefixes tell you these were identified in Latrodectus, the black widow. There is a lot of similarity in the venoms of black widows and false widows! That α-latrotoxin is the one that we vertebrates have to worry about. Do we need to worry about our common house spiders? Maybe a little bit.

We reveal the striking similarity between the toxins found in Steatoda nobilis venom and that of black widow spiders (Table 1). The most powerful toxin classes (α-LTX, α-LCT, α,δ-LIT) and the enzymatic machinery allowing the venom to more easily spread into the prey (metalo and serine proteases, chitinases) are both present in large quantities. This however does not mean that Steatoda is as dangerous to human beings as some members of the genus Latrodectus. If isoforms of potent toxins are present, our study does not provide information about their potency. Evaluation of toxin toxicity would need to be performed before any conclusion could be reached. Nevertheless, given the composition of the venom depicted in this study, S. nobilis should be considered a species of medical importance and there is no doubt that S nobilis (with Latrodectus tredecimguttatus) is one of the most dangerous spiders in Western Europe.

The easy solution is to not get bit. That’s not hard to do at all, these spiders are really not interested in you. Leave ’em alone, they won’t bother you.

If you are bitten — I’ve heard it’s a bit like a bee sting, although personally I’ve never experienced it — if you experience a strong reaction, the similarity to Latrodectus means black widow antivenin will be effective. As the paper says, though, they have nat assayed the potency of Steatoda venoms, and what I’ve heard is that they’re not as fearsome as black widow venom, so don’t panic. Besides, only one or two people a year die from the bite of the most deadly American/European spider, the black widow, while Steatoda has milder effects.

If you’re still worried, here’s a summary of recommended first aid. Wash the bite (infection is probably a greater danger than the toxins), use an antibiotic cream, and ice the area. Take ibuprofen and/or an antihistamine.

This is rather interesting: an article from the National Museum of Ireland describing the appearance of the noble false widow (Steatoda nobilis) in that country, in the late 1990s. I haven’t seen any of that specific species in my neighborhood, but apparently they are a significantly invasive species. We have lots of Steatoda and Parasteatoda here, though!

Most of us in Ireland have heard about this recent arrival, but few would know its scientific name, Steatoda nobilis. This spider is more commonly known as the noble false widow.

Interestingly, in an article published at the time (Nolan 1999), Myles Nolan tells the reader that a couple of weeks prior to the aforementioned Bray discovery, another person had found a great number of these spiders on their own property, approximately 250m away from the Bray residence. The author observed at the time that these spiders have a high reproductive rate, and that the spiderlings are inclined to disperse widely from the egg sac, perhaps accounting for this species’ ability to colonise easily.

The Museum specimen detailed in our acquisition register is, however, the first valid Irish record as an identified specimen was lodged with the Museum. That specimen (called a ‘voucher specimen’) is now stored safely in the Museum and is available for study and research.

As Ireland currently houses relatively few animals who pose a risk to human health, this new arachnid is now of great curiosity to the public. The reports, however, are over emphasised, and there is little for humans to fear from the noble false widow.

A recent report from the Irish scientific community however, showed that a common lizard had been preyed upon by this diminutive spider (Dunbar et al. 2018). The young lizard was discovered wrapped in spider webbing, with the noble false widow crouched over its head, presumed to have been feeding on it – a potential worry for Ireland’s only native terrestrial reptile.
The noble false widow can now be found in at least 17 Irish counties, all year round, both indoors and out (although more so the latter). They have a strong tendency to live on manmade structures and materials, such as steel, concrete and timber. Sheds, outhouses and boundary railings provide the perfect habitat for our new arrival.

Part of the reason for the relatively sudden appearance of Steatoda nobilis in the scientific eye, though, is the British tabloids, which had an absolute freakout over big spiders, playing up the nearly non-existent dangers and clutching their pearls over the observation of a few spiders near one of the Queen’s estates. It was ridiculous.

I can vouch for Steatoda‘s eagerness to disperse — when I found the newly emerged clutch of spiderlings yesterday evening, they had nicely spread out equidistant from each other in their container, and when I opened it up, the race was on, with all the spiderlings on the edge of the mass rushing to get out into the larger lab. I think they don’t much care for their brothers and sisters.

The “high reproductive rate”, though, is a relative thing. My impression of Steatoda triangulosa and Steatoda borealis, the local species in the genus, is that they were sluggards compared to Parasteatoda. They take a month to develop from egg to spiderling, compared to Parasteatoda‘s week and a half, and they have much smaller clutch sizes than Parasteatoda. I’ve been sitting here feeling like the Steatodas take forever to get to the point I can work with them.

On the other hand, at the end of that month I am finding myself drowning in baby spiders…

I’m learning things from raising Steatoda triangulosa. Feeding time is a marvel: I recorded a very short video of the little spiderlings’ reaction to having a fruit fly thrown at them. It’s like instant implacable carnivory! They’re eager to leap onto their prey, exhibiting the same behaviors as the adults.

So, this is my idea of a good parenting book. Take your little human baby, and toss a small calf or a large puppy into the crib with him or her. Leave them to their business for a few days. Come back later and remove the bones and scraps, and toss them another one. Repeat until they’re old enough to hunt on their own.

I guess since they’re weak humans, you could give the baby a Bowie knife or something to compensate.

Unfortunately, my own children are all growed up, and it’s too late to try on them. My kids probably won’t let me try this with the grandkids. That means…

I know I was worried about feeding my spiders — they’re so tiny, 1.2mm long, and fruit flies are huge, maybe 3 times that size — so some of you must have been worried. Also, don’t worry, no photos in this post.

I went in to the lab to feed them this afternoon, and I shouldn’t have been concerned. Every one had fiendish, cunning traps strung across their containers, and when I tossed a fly in, they were on them instantly, wrapping them in silk and biting them and sucking out their succulent juices. I’m used to adults being so voracious, but young Parasteada are usually more passive and clumsy. Steatoda triangulosa seem to emerge from the egg sac with their killer instincts already primed.

One somewhat surprising observation: I was curious how the adults get their distinctive zig-zag stripe on their abdomen. What I’m seeing so far is that the spiderlings emerge with pale abdomens, which then darken up fairly uniformly. Today, in the 5-day-old spiderlings, I saw a set of white spots along their abdomens. It’s possible these spiders don’t have a dark zig-zag stripe at all — they have dark bodies (like other familiar Steatoda species), and then they make light-colored triangles to create the stripes.

I’ll be watching closely over the next few days. I also have another egg sac that is darkening up and will probably spawn another set of babies for me to play with.

Checked on my collection of S. triangulosa egg sacs this morning. The one I’ve been waiting on for 27 days hasn’t yet opened up, but it looks distinctly different — it’s a black mass with little hairy black legs poking up, surrounded by cottony fluff. The spiderlings are making me wait longer. I was tempted to pull out my forceps and extract them by force, but I’m waiting to see what the normal developmental time at 28°C might be, so no shortcuts allowed. Any day now, as I’ve been saying for a week.

Then I checked on their momma. I’ve moved her into a separate, larger container now, and the other day I fed her a big juicy mealworm…which immediately thrashed it’s way out of the web and fell to the container floor. The web was pretty much shredded at that time, and I couldn’t stick the worm into it, so I left it there and figured I’d move it today, when the web was repaired. Usually, Parasteatoda ignores food that doesn’t land in a web, and I figured she’d be the same. They’re rather passive predators.

I was wrong! S. tri is willing to get down and dirty, had dived in snared the mealworm, and then hoisted it about 10cm up. It was dead, dangling, with a black ring in the segment that the spider had bitten and sucked out its juices.

Good work, mom. Then I sought out the spider, who was now nearly spherical again. I’ll spare the arachnophobes that image.

Then, to my surprise, she had spent last night laying another egg sac!

That’s 5 in 4 weeks. I’d wondered how they kept their population up compared to P. tep, since their egg sacs hold a fifth the number of spiderlings. There’s the answer: they make it up in volume.

This was then, two days ago.

This is now.

The spiders have gone through their final molt before emerging — each of those white blobs is the shed cuticle of one spider baby. They’ll be coming out soooooon. Even now as I watch them, I can see them twitching, like sleeping puppies dreaming of sucking the blood out of their prey.