Big game hunters

Spiders in the genus Theridiidae (and their cousins, Latrodectus) are well known for hunting and eating prey much bigger than they are, including vertebrates. Here’s a vigorous specimen of Steatoda nobilis trussing up a shrew, which she then reduced to skin and bones over the course of three days.

I’m sad to say that we don’t have S. nobilis where I live, but there’s hope — they’re spreading across the country. Our spiders in my region can get fairly big (especially S. triangulosa) but they’re still a little smaller than S. nobilis. All Theridiidae have neurotoxic toxins in their venom.

Considering the range expansion and population densities achieved by S. nobilis over recent decades, it is unsurprising that the species utilizes its full repertoire of predatory tactics as it continues to adapt to new territories and exploit available resources. As this species continues to spread, such events of vertebrate predation are likely to increase. This contribution validates that S. nobilis is a habitual rather than an occasional vertebrate eater, thus demonstrating the potential impact of S. nobilis on native organisms and the continued need to closely monitor this species.

Don’t worry — you’re not on the menu, yet.

They like to eat things that are bigger than they are

I should save that title for a horror novel.

The other day, I switched my juvenile Latrodectus from a diet of nice snackable fruit flies to huge, relatively speaking, mealworms. I posted a photo of that right here.

I was curious to see how they would cope with such a large prey item. No problem! Here’s the result: the mealworm was sucked completely dry, leaving nothing but a transparent tube of cuticle.

I don’t know how they do it. The prey animal was completely hollowed out. Maybe I’ll have to try to capture it in timelapse.

All for moi?

Yesterday, I started moving the larger juvenile Latrodectus to their very own special homes, and I give them a day to build a cobweb before giving them a homecoming meal. This young lady got handed a whole mealworm — imagine giving a teenager a whole cow and permission to kill and eat it. That’s what this was like.

She kept tapping it like she could hardly believe it was all hers. She’s been living on fruit flies for the past month or so, so this was like a miracle meal plopped into her lap. If spiders had laps.

Notice how she has the white juvenile markings on her dorsal abdomen. Those will fade. She also has a red hourglass on her ventral abdomen, which will not.

Needs more spiders

A reader sent me a comment about how Catholics tell stories that they claim are in the Bible that aren’t, and that specifically they don’t include spiders. I had to double check. Here are all the Bible verses that mention spiders.

Pathetic. For one, they’re about spider webs, not spiders, and the second one is about lizards. Do they think lizards and spiders are the same thing? They’re so desperate to pad their list of spider facts from the Bible that they include reptiles.

Speaking of padding, here’s my correspondent’s tale of Catholic fable-making.

I made a comment on Bluesky that it wasn’t until I was studying the Bible in Religion class at a Catholic High School that I realized how many of the stories I was told by nuns in grade school weren’t actually in the Bible. I gave, as an example, the story of how Jesus, Mary, and Joseph, in their flight to Egypt to escape Herod Antipas’ attempt to kill all potential Kings of the Jews, they hid in a cave from pursuing soldiers. After they entered the cave, spiders spun webs across the entrance to the cave causing the soldiers to believe that the Holy Family couldn’t have possibly entered the cave.

A commenter wondered if the story I related was inspired by a similar one about David fleeing from King Saul for the exact same reason. Unlike the story about the Holy Family, the tale of David hiding in a cave, minus the spiders, is actually in the Bible.

I interpret this to mean Christians realize that there is a serious lack of spider relevance in their holy book, and they are crying out for more.

Not the prettiest jumping spider I’ve seen

I’m used to seeing spectacularly pretty Australasian jumping spiders, and this one, the genus Simaetha, isn’t exactly dazzling.

Australian representatives of the two extant Simaethina genera: A, C, E, Simaetha sp. (female); B, D, F, Simaethula sp. (female). Specimens are shown in dorsal view (A, B), lateral view (C, D) and frontal view (E, F). Scale bars: 0.5 mm (B, D, F), 1 mm (A, C, E).

This one, though, has the excuse that it’s between 11 and 16 million years old. It isn’t that old — I’d expect that the planet had lot of jumping spiders during the miocene — but it’s nice to seen an example from that period.

Simaetha sp. indet. (AM F.161027). Only known specimen: A, light microphotograph. B, scanning electron micrograph. C, morphological interpretation of light and electron micrographs. Abbreviations: LL, left leg; RR, right leg; AME, anterior median eye; PME, posterior median eye. Scale bars: 0.5 mm.

It’s also impressive that they could sort out what was what in the squashed bits of that fossil.

On the 8th of October…

…one should spend some time with one’s spiders. I know it is numerically the 10th month, but it should be the 8th month by name, if not for some silly Romans who tried to squeeze a couple more emperors into the calendar. It was feeding day anyway, so I spent a little time giving them treats in celebration.

Here’s Blue, who gobbled down her mealworm instantly, and is now dabbling her toes in her water dish.

It’s getting more difficult to photograph Blue, because she’s covering everything with silk — when you look in from the side, it’s a haze of strands everywhere, and I have to remove the lid to the terrarium to lean in and see what she’s up to.

I fed the Steatoda borealis, the Parasteatoda tepidariorum, and the Latrodectus mactans juveniles as well. I’ve isolated about 80 black widow juveniles in individual vials, and am running out of room in the incubator, so there’s about 80-100 more left in a container together, like a giant colony of black widows. It’s a Darwinian world in there — I figure I’ll let the numbers decline and then extract the biggest survivors.

One thing I’ve noticed is that the isolated individuals, in spite of getting a bounty of fruit flies twice a week, are growing more slowly than some of the black widows in the communal container. Most are small, but there’s a few that stand out as growing distinctly larger than their siblings.


(Photos were taken immediately after I dumped a lot of fruit flies into the container, so they’ve all got their faces snout deep in dinner.)

I have to speculate that maybe, just maybe, some of the spiders are eating their siblings.

Spider gynandromorph!

Arachnologists poking around in Thailand discovered a new species of mygalomorph, Damarchus inazuma. One individual was particularly unusual: it’s a gynandromorph!

Damarchus inazuma sp. nov. gynandromorph (ARA–2021–273). A dorsal habitus (live); B dorsal habitus (preserved); C ventral habitus (preserved). Scale bars: 1 cm (A, B, C).

Female side is on the left, male on the right.

Kunsete, C., Thanoosing, C., Sivayyapram, V., Traiyasut, P. & Warrit, N. (2025) New insights into Damarchus: a new species and gynandromorph description from Thailand (Araneae: Bemmeridae). Zootaxa, 5696 (3), 409–424. https://doi.org/10.11646/zootaxa.5696.3.6