Dolomedes vittatus Egg Sac

[Dakota Ross]

A few weeks ago I caught what I beleive to be an adult female D. Vittatus and have enjoyed watching her feed. Today I was surprised to find out that she has crafted an egg sac. Having never cared for an arachnid before, only reptiles and amphibians, I naturally have several questions as I want to learn more about this beautiful girl!
1. How likely is it that the egg sac is fertile and will hatch considering the spider has been in captivity for approximately 3 weeks?
2. Does the egg sac need any special care?
3. Assuming the egg sac does hatch, what would be the best method to house and care for the spiderlings?
Thank you in advance for any and all input!

 

[chanda]

Because she was wild-caught as as adult, there's a pretty good chance that she has mated and the egg sac is fertile - but it is not a certainty. Three weeks in captivity is nothing as far as being fertilized is concerned. Many female spiders retain sperm and can lay multiple fertile egg sacs over a period of months after even a single mating. I have had wild-caught black and brown widows produce as many as 6 or 7 fertile egg sacs. I had a wild-caught wolf spider (Hogna carolinensis) that gave me 3 fertile egg sacs and a wild-caught Trechalea gertschi that produced two fertile egg sacs. On the other hand, my wild-caught Selenops turned out to be infertile. She gave me 9 egg sacs, but all of them were duds.

As far as taking care of the egg sac goes, just leave it with the mother. Dolomedes belong to the Nursery Web spider family (Pisauridae) and will care for their eggs. Just be sure the enclosure you have her in is as close to escape-proof as you can get it by the time the eggs hatch. The babies will stick close to Mom for the first few days - but then they will want to disperse. They will be small enough to escape through the tiniest cracks or ventilation holes - and may even be able to slip through the mesh of the screen. (Both my Hogna and Trechalea hatchlings were able to do so.)

Once the spiderlings are ready to disperse, you may want to separate them. If you leave them together, they will eat each other. (Of course, this does help to get their numbers down to manageable levels while simultaneously solving the problem of feeding them and weeding out the weaker ones.) They will need small prey like fruit flies or newly hatched crickets.

For housing, plastic deli cups with ventilated mesh lids work well. What I'll usually do is cut a 1/2 inch hole in the top of the lid and stuff a piece of sponge in the hole to plug it. When I want to feed or water the spider, I don't have to remove the entire lid - I just pull out the sponge and drop flies through the hole. They'll also need a bit of substrate in the bottom like sphagnum moss or coconut fiber to retain humidity and they should have a bit of bark or some twigs or something to climb on.