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Black-and-Yellow Argiope Spiderlings Hatching

Some species of spiders (including wolf and jumping spiders) overwinter as young adults and mate/lay eggs in the spring. Many spiders, however, mate in the fall, after which they lay eggs and die. Their white or tan egg sacs are a familiar sight at this time of year. One might assume that these species overwinter as eggs inside their silken sacs, but this is rarely the case as spider eggs can’t survive being frozen. Spider eggs laid in the fall hatch shortly thereafter and the young spiders spend the winter inside their egg sac.

Although egg sacs provide a degree of shelter (the interior is packed with very fine, very soft silken threads), the newly-hatched spiderlings do have to undergo a process of “cold hardening” in the fall in order to survive the winter. On nights that go down into the 40’s and high 30’s, these young spiders start producing antifreeze compounds, which lower the temperature at which they freeze. By the time freezing temperatures occur, the spiders are equipped to survive the winter inside their egg sac – as spiderlings, not eggs.  (Photos:  Black-and-Yellow Argiope egg sac and spiderlings – egg sac had been pecked open by a bird)

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6 responses

  1. Kathy D

    Wow, I never fail to learn something from these posts! I’ve seen many egg sacs and have long wondered about the lifecycle of spiders. This is very cool.

    November 9, 2020 at 8:15 am

  2. Alice

    How are the spiderlings going to survive, if the egg sac has been (pecked) open?

    November 9, 2020 at 8:21 am

  3. Rita Pitkin

    Are these what are called “garden spiders”? Fairly large, black, bright yellow?

    November 9, 2020 at 8:58 am

  4. Yet another very interesting post! I had always assumed those egg sacs were full of tiny eggs, waiting for spring, to develop into spiders. But no! They’re filled with teeny spiderlings that have created their own antifreeze and are waiting patiently, each in its own sac, for the end of winter. Wonderful!

    November 9, 2020 at 9:23 am

  5. Char Delabar

    >

    November 9, 2020 at 11:34 am

  6. Kathryn

    They’re cute when they’re little!

    November 9, 2020 at 2:06 pm

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