Our compost bin is thriving! We found some new egg sacs inside it, like this one:

It’s strange. It’s orange. We suspect it might be Mimetus, the pirate spider, but time will tell. I took it into the lab and will have to wait for it to hatch out.
The other compost development is that it is full of squirmy busy maggots. I’m talking dense sheets of a multitude of swarming maggots. I scooped up some and brought them in to see if the spiders would eat them. They liked it! (The spiders, not the larvae.) This will be an alternate food source, at least over the summer. I think it’ll slow down a lot once the temperature drops below freezing.
In other news, I’ve been doing weekly measurements of the growth of my Steatoda triangulosa babies. They’re all (except one, sort of) growing well. Here’s a table of the mean dimensions of the young spiders.

I know, not exactly exciting, and I have to plod through more weeks of measurements. Note the big surge in length this week! That’s because they all molted on Day 22, and shedding that exoskeleton gave them more room to stretch.
I mentioned one spider was an exception. Spider #5 is looking a bit odd. Still growing, but suddenly their limbs and palps have gone pale…I’m hoping they’re not sick.

I’ve been tracking the growth of individuals in my Steatoda triangulosa colony, and finally have a whole 3 time points so I can estimate the spider growth rate. Behold, the first preliminary chart!

The line is a linear fit, which is not likely to be what I see in the end, but it’s optimistic, and I can’t really make many assumptions with so little data. But OK, if aiming to raise these spiders to a length of 1 meter, that’ll only take, with that assumption, about…a century? Yikes.

That rate is perfectly appropriate if they max out at 10mm long, like their mommy, but it’s going to be hard to take over the world with tiny little spiders like that. I guess I’ll have to go for numbers.

Hey! I was watching my spiders do this just yesterday!

It was a feeding day. Little critters like Drosophila are easily handled — I saw one swoop down on a drag line to a fly walking on the floor, hog-tie it with a couple of quick flicks of silk, and then haul it up in one smooth motion. That was impressive.

However, these guys do kill and consume prey many times their size. I saw one snag a mealworm, which then went into a frantic writhing struggle and broke free, ending up on the floor of the container. The spider dived on it, trussed it up again, and then hoisted it up about 10cm to the heart of its cobweb. They are amazingly strong, and as the diagram illustrates, very clever about leveraging the structure of their web to secure their prey.

I have not tried feeding them small vertebrates yet, but the lab next door to mine is a herpetology lab, full of spider food. Don’t tell Heather Waye, she isn’t personally keen on spiders already, and hearing that they might have designs on her research animal would not be very endearing.

OK, I’ll stick to invertebrates.

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…