I’m still regularly collecting data on growth rates in Steatoda triangulosa. Here’s what it looks like on day 39 (dark red line is the mean, I’ve included data for individual spiders in a lighter color to illustrate the variation):
They’re now at about, or over, half the adult body size, and are looking fairly mature. The palps haven’t fully matured, so I can’t sex them very well, but the ones I suspect are male — they just have a bit of a bulge — are on the smaller size. The couple that have really taken off look very female to me so far.
I’m discovering all kinds of complications, though. In particular, size is definitely a function of feeding. I gave them all a mealworm earlier this week, and some of them look hugely rotund right now. Fruit flies are definitely not adequate for the full nutrition of a growing spider, so it looks like I’m going to need to spruce up the mealworm colony soon. I’ve got another S. triangulosa egg sac that has reached the stage of seething darkness, which means I’ll have more babies this week.
Also the pigmentation is distinct and strong, and now it’s obvious that these spiders have white triangles on a dark background, rather than dark stripes on a pale background. This next batch of babies are going to require daily mapping of pigment patterns so I can see exactly what’s going on. I’m about to post a few photos on the Patreon page, if you want to see.