Humpback Orb Weaver Spider – Eustala sp.


Humpback Orb Weaver Spider – Eustala sp.
Family Thomisidae – Crab Spiders
Live spider photographed in the wild at Oregon, Illinois.
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Humpback Orb Weaver Spider
This tiny (5mm) unfortunate spider has become host to some sort of parasitic larva –  you can see the white, worm-shape on top of the cephalothorax under the overhang of the abdomen. Some have suggested it may be a mantid larva or perhaps some sort of wasp larva. It could be a parasitic fly in the family SyrphidaeTachinidae, or Phoridae (the flies that infect the domestic honey bees). I will visit her every day and maybe see what happens. (She disappeared 2 days later.)

This from the Atlantic magazine online: "Consider Polysphincta gutfreundi, a parasitic wasp that grabs hold of an orb spider and attaches a tiny egg to its belly. A wormlike larva emerges from the egg, and then releases chemicals that prompt the spider to abandon weaving its familiar spiral web and instead spin its silk thread into a special pattern that will hold the cocoon in which the larva matures. The “possessed” spider even crochets a specific geometric design in the net, camouflaging the cocoon from the wasp’s predators."

Orb weavers comprise a huge family of spiders, with 3500 species worldwide, 180 of which call North America home. These spiders vary greatly in color and size, measuring 2 – 30mm (1/16 — 1 1/4") long.

Humpback Orb Weaver Spider lateral view
This lateral view shows why the name "humpback orb-weaver"
Humpback Orb Weaver Ventral view
Ventral view
Humpback Orb Weaver Spider
Tiny subjects present challenging opportunities in macro photography
Humpback Orb Weaver Spider
Tell me this gal does not look sad and forlorn!
The oldest fossil record of an orb-weaver is from the Lower Cretaceous. Several fossils provide direct evidence that the three major orb weaving families; Araneidae, Tetragnathidae and Uloboridae evolved  140 MYA..

orb-weaver spider with parasite
Another orb-weaver, another parasite. This is getting ridiculous!
Wondering how to get that bug identified? Please see the kind folks at Bugguide.net. (North America)
North American Insects & Spiders is a website dedicated to macro photography of live organisms in situ.
References

  1. Bugguide.net, "Humpback Orb Weaver"
  2. Eric R. Eaton, the Balabans, Lynette Schimming, Jeff Hollenbeck, Chuck Entz, kschnei, Bugguide.net, "Genus Larinioides – Furrow spiders"
  3. Wikipedia, “Spider
Class Arachnida / Order Araneae: Spiders are the largest group of arachnids.  They are easily recognized by their eight legs, and there are few creatures great or small that elicit such irrational fear in mankind. The vast majority of spiders are completely harmless and offer beneficial services, chief of which is keeping the burgeoning insect population in check. I am continually amazed at the resourcefulness of these supremely successful predators. Spider Index | Orb Web | Nursery Web