I picked up this large mama wolf spider with her egg sac while out doing field work. The trip home apparently disturbed her, because I was disappointed to see she dropped her egg sac and apparently abandoned it. Then a few days later it vanished. Then she constructed a refuge of webbing coated in dirt and debris and closed herself in. A few more days later I noticed she had an egg sac again–and it was bigger than ever. Intrigued, I sent the picture above to friend and former post-doc in my lab Shawn Wilder. Shawn introduced me to working with fire ants and also happens to have done his Ph.D. work on sexual cannibalism in wolf spiders.

Shawn had this to say:

Beautiful spider. It looks like the genus Hogna, most likely Hogna carolinensis (they’re one of the more common big Hogna in Texas). I studied Hogna helluo for my Ph.D. but they’re not quite as pretty as carolinensis because helluo doesn’t have the mottling on the legs. That’s typical Hogna behaviour. They will build a silk-lined burrow and will eat their egg sacs if they lose sight of them and refind them. It looks like she is trying to warm up her egg sac in the sun. That’s a mega-huge egg sac she has. It should be very fun when the babies crawl out and onto her body because when there are tons of babies the mom has to use her pedipalps like windshield wipers to keep the babies away from her eyes!

I had managed to completely forget that wolf spider mothers carry their babies around on their backs so I was pretty psyched. And mama spider delivered this week.

Shawn also pointed out that the spiderlings don’t need to eat at this point. For a week or two they ride around on their protective mother, clinging to special barbed hairs, and then gradually begin to disperse. Every so often a few spiderlings will drop off and walk away from the mother, providing a very effective way for the young to disperse over a wide area in nature. Of course, if sufficiently disturbed the spiderlings may scatter early–probably accounting for urban legends of wolf spiders that “explode into little spiders” when stepped on.