Monday, August 29, 2011

A Silvery Thief - The Dewdrop Spider

This weekend I was in the garden trying to take pictures of halictid bees. Where I grew up in the upper midwest, we used to call these solitary insects "sweat bees." Sweat bees are pretty aggressive. I remember friends of mine in sheer panic when one landed nearby as everyone had at one time or another had been stung. In Florida, these colorful bees mind their own business. Here is the one picture that was clear. She is feeding on a tropical milkweed (Asclepias curassavica). Male halictid bees, by the way, have a yellow and black striped abdomen, but their thorax and head have the same metallic green color.

Halictid Bee

I have also been watching all of our garden spiders, Argiope aurantia. The number of egg sacs are quickly muliplying up underneath our eaves.

Argiope aurantia

I was very excited to see a tiny pair of Dewdrop spiders (Argyrodes sp.) I think they are Argyrodes elevatus, but I'm not positive. To give you a sense of scale, the Argiope spider is approximately 20mm. The Dewdrop spiders are 2mm.

Argyrodes sp.

The silver dewdrop spider is a kleptoparasitic spider. They don't weave their own webs. Instead, they hide on the periphery of another spider's web, typically a large spider such as Argiope or Nephila. They wait for the larger spider to make a kill, then sneak in for a clandestine meal. It is dangerous work I'm sure. What these pictures don't capture very well is the brilliant silver of their bodies. As though lit from within, they shine brightly in the sun like polished jewelry. They are very obvious as you approach the web, but obviously the host spider either doesn't see them or is unconcerned with the tiny thieves.

Argyrodes Female

Argyrodes Male

It turns out that the dew drop spider is capable of killing its host, or at least considers the host a food source. Here are some photos of one feeding on an Argiope.

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