Monday, July 8, 2013

Silver Dew Drop spiders: more dangerous than previously thought?

I've shown you photos of the dew drop spiders that frequent the Argiope spider webs around my home. These small, silvery spiders are kleptoparasitic of larger spiders such as the Argiope and Nephila. That typically means that they steal prey from the host web that is either too small for the large spiders, or it is unattended larder.

This evening though, I found a dew drop spider (Argyrodes sp.) feeding on the carcass of an Argiope female. The Argiope had molted earlier in the day. Did the dewdrop spider attack and kill the Argiope before its exoskeleton hardened? Or did the Argiope die from a failed molt and the dewdrop simply took advantage? I wish I had witnessed the whole event so I would know the answer.

Dew drop spider on the bottom. Her fangs embedded in the face of the Argiope. Molt on top.


Close-up of the dew drop spider feeding on an Argiope female

8 comments:

  1. In your first picture the abdomen looks a little more dehydrated than you would expect just from a molting. It reminded me of one particular garden spider who made her home on my back porch when fall came she started fading daily, her abdomen was the first thing to 'wither' so to speak. I can't imagine the little drop spider causing that even after hours of feeding. A failed molting seems most likely?

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    1. I agree. Her abdomen was deflated. I'm almost wondering if the garden spider was catching enough food. I don't recall seeing that particular web with any prey. She had no eggs either. Maybe she was sick in general.

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  2. I live in Virginia on an acre of land and the garden spiders are typically in every corner of my yard. This year however I've only spotted a few small juveniles and usually by this time they are well into 'adult hood' do you think there is any correlation with the mass bee die offs or it's just not the year of the garden spider?

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    1. My guess is normal population fluctuation. I see similar things in my yard every year, except for mosquitos, there always seems to be a lot of mosquitos. Localized insect populations are very hard to predict and can fluctuate wildly from year to year. I used to have a lot of Anisomorpha walkingsticks in my yard. It was difficult to imagine them ever disappearing due to all of the egg-laying every year. But now, I hardly see any.
      Your garden spiders may be back next year. or it may take them ten years to return.

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  3. Well I hope it doesn't take them 10 yrs! I walked around tonight looking in the nooks and crannies of my yard and I counted 10 juveniles, however the mosquitoes and yellow flies were unbearable so I gave up. There is still hope for them yet just seems a little late in the year to still be so small.

    On another note do you ID bugs at all? I have a picture of one that I am unable to identify.

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  4. I can sure try to ID one for you. Send me a pic and location.

    Everything is weird timing-wise this year it seems. Flowers too early or too late. That sort of thing.

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  5. Thank you so much! I have sent it to the email provided here.

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