Do true spiders (specifically Agelenopsis sp.) lay infertile eggs?

[LordAnon]

So the Agelenopsis sp. Illinois I caught in the last couple of months or so wove some kind of egg sac, and with flashlight, I can definitely see something yellow inside. I don't know if she mated before I caught her, but I definitely haven't bred her. Could she have been waiting this whole time to lay eggs? Is it possible for them to lay eggs without mating?

 

[chanda]

While I can't personally speak to Agelenopsis, there are plenty of other spiders that will lay eggs whether they've been fertilized or not, so I would imagine Agelenopsis will do the same.

In my personal collection, I've had several species of orb weavers, wolf spiders, black and brown widows, huntsman spiders, lynx spiders, and jumping spiders that have laid egg sacs that were duds. Most were wild-caught as sub-adults and subsequently molted in captivity or were captive-raised, so they were not mated and the eggs were infertile. I've also had all of the above that were wild-caught as adults and had presumably mated prior to being collected that eventually laid fertile egg sacs that did hatch out.

There have been some observations of parthenogenesis in spiders, but these cases are rare. However, it is not at all uncommon for mated female spiders to store sperm for extended periods and still lay fertile eggs months later. I've had black widows lay seven or eight (or more) fertile egg sacs without mating in between. One of my fishing spiders laid two fertile egg sacs while the other laid three.

If your little grass spider was already mature when you caught her, there's a good chance that she had already mated and that her eggs will be fertile.