Wolf spider with eggs

2011 April 23

Wolf spiders are very common in our yard, and are particularly noticeable in the spring before the grass grows up. We found this very well-camouflaged one on May 6, 2010, carrying what looked like a little pebble attached to the end of her abdomen.

That’s actually an egg case she’s carrying. This is the typical behavior for wolf spiders: after overwintering as adults, they lay eggs in the spring and the female carries them around for safekeeping. In May, it generally only takes a couple of minutes to find female wolf spiders carrying eggs around in the grass. The other feature telling us that this is a wolf spider, is her large (for a spider) eyes.

We had hoped to keep her until the eggs hatched, so that we could get pictures of her carrying around her brood of hatchling spiders on her back. Unfortunately, I made the jar too moist [1], and her egg case got moldy, at which point she abandoned it. This was quite sad. We let her go afterwards, but I have no idea whether they can lay a second batch of eggs if something happens to the first batch. Probably not.

We may try raising up an egg case again this spring, only this time I’ll be more careful about the moisture control. [2]

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[1] What we normally do to keep spiders is put them in a transparent plastic jar, with a lid made out of window screen, and put in a piece of paper towel or a cotton ball moistened with water. This has worked really well for spiders that have hatched, but evidently is too moist for eggs.

[2] Next time, I may try putting down a layer of moist soil, with dry sand on top of it. This should help keep it from drying out entirely, but will also keep the egg case from resting directly on moist soil. If someone has a better setup for hatching spider eggs, I’m all ears.

4 Responses
  1. April 23, 2011

    I wonder if the silk covering the egg sack is high in sugars (starches?) and particularly prone to growing mold. I love the middle photo, too. I can just hear her asking, “Does this egg sack make my butt look big?”

    🙂

  2. April 24, 2011

    A practical question for you, Tim, that popped into my head as soon as I read you intended to hatch a spider egg sac: Where are you doing this? If the lid of your jar has ventilation made out of a window screen, would baby spiders be able to crawl through those holes? Are you concerned about spider infestations?

  3. April 25, 2011

    Last question first: No, I’m not particularly concerned about spider infestations. If nothing else, they help keep the fungus gnats down. And, the plan is to let them all go outside before they get old enough to hop off of Mama’s back.

    For the first question, while I have been using window screen on the jars, I think I’ll be switching to something else. McMaster-Carr sells little pre-cut discs of screen with a range of opening sizes, and I’m planning on getting a bunch of them with about half-millimeter openings in the mesh. This will be fine enough to keep in things like fruit flies, and will also be useful for other projects, like making sugar syrup buckets for supplemental feeding of bees.

  4. Della3 permalink
    July 31, 2011

    Why the moisture? I’ve seen a number of batches of newly hatched spiders, and none of them were near any water sources. I know the adults need to drink and thus find their way to my shower sometimes, but the babies have always hatched above ground, away from water. Granted, this lady is carrying her babies with her, but if her eggs are prone to fungus, I imagine she would steer clear of water as well. Even a humid environment might be undesirable. Perhaps a dry environment with a drop or two of water each day from an eyedropper for the mother would be best. Regardless, since they are plentiful, you can try hatching more than one batch in different environments.

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