Sunday, November 18, 2012

An Earwig Mother?

While looking for slug eggs today, I uncovered a female earwig (Forficula auricularia) in her burrow, but almost missed the cluster of tiny yellow eggs nearby! Now, I was surprised that the eggs weren't in the burrow and that she sought to protect herself instead of them, running away from me instead of rushing to them. I read that earwig mothers show maternal care for their eggs, protecting them until they hatch, so I was disappointed that this mother exhibited such selfishness and negligence. However, I have two hypotheses about this: (1) I was so near the eggs that perhaps the mother didn't have time to reach them before I did, or (2) These eggs were laid not by an earwig but by a slug (Lehmmania valentiana lays yellow eggs, though these should be more oblong if they are). So, I think I'll check on the situation again tomorrow and see what happens.

I used my flash to see inside the burrow, in case the earwig was guarding some eggs in there (at this point I hadn't noticed the yellow cluster on the right). I peered as hard as I could into that hole, but I couldn't discern anything definitive.


My confusion began when I discovered the eggs. You can see that a large area has been carved out of the soil, but were both wings dug by the earwig? Are those really her eggs? Then why didn't she protect them from me, a potential predator? And why aren't they in the deeper burrow?


Anyway, earwigs lay their eggs as early as November, so it's very possible these could belong to the female I found. The temperature determines the length of time before the eggs hatch. Since we don't get especially cold weather down here, hopefully I won't have to wait too long for them to hatch.

Here are some sites about earwig "motherhood":
http://greenopolis.com/myopolis/blogs/northern-woodlands/earwigs-remember-them-next-mothers-day
http://www.earthtimes.org/nature/earwig-mothers-parental-care/1946/ (evolutionist bent, but interesting study)
http://www.readbookonline.net/readOnLine/34003/

And general biology:
http://www.downgardenservices.org.uk/earwig.htm
http://www.arkive.org/common-european-earwig/forficula-auricularia/
http://bugguide.net/node/view/23281

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