widow egg sac
I wrote a while back and asked about keeping a young black widow I found in a box of supermarket firewood. I have had her now for several months, and have been keeping her in a container that has six 2-3mm holes for air. She’s quite happy – I feed her all sorts of other bugs and sometimes pet store crickets. This morning I found her patting the last layers onto an egg sac – YIKES! How did this happen? Was it possible she had bred already, even when she was a wee cm long (including legs!)? Or has she figured out how to bribe the cat to unscrew the lid to her bottle and goes out on the town at night? Hussy! In any case, what do I do now? Take it all out to the woods and let her go? I’d hate to have them running around the neighborhood – lots of little kids. here are a few photos of the little minx.
Syndi Burton
San Francisco

Hi Syndi,
First, we love your colorful letter. Minx is such an underused, descriptive word. We believe it is possible that your Elvira was fertilized prior to becoming your pet. She wouldn’t have begun to swell with eggs until she was well nourished, and we believe she probably had a more regular diet with you than she would have gotten in the wild. It is also possible that the eggs are unfertilized and non-viable. To be safe, to the woods with Elvira might be the kindest solution to the riddle. Eric Eaton wrote in to add this: “Everything else looks in great shape:-) You are right about the female widow, by the way. Female spiders (and most insects, too) can store sperm from one mating and it lasts them a lifetime. Further, female spiders (and moths, etc) will lay eggs regardless of their viability, especially toward the end of the female’s lifespan.”

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