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Monday, November 5, 2012

Juvenile Southeastern Field Cricket?

Turning over a stepping stone a couple of weeks ago, I discovered a dark, wingless cricket with downward-curving cerci and no ovipositor. I believe it is a juvenile Gryllus rubens, or Eastern Trilling Cricket (also called Southeastern Field Cricket), a member of the subfamily Gryllinae, or Field Crickets. As always, if I've identified this specimen incorrectly, feel free to make the proper ID. Unfortunately field crickets are very difficult to distinguish morphologically and often they can only be specified by subtle differences in their songs.

I'm not sure why the cerci are curved like that. They should stick straight out. I haven't been able to find any images of crickets with similar cerci. Could this be a defect/mutation of some kind?
You can see the beginning of wings just below the pronotum (protecting the thorax). This feature indicated to me that the cricket was not fully developed, as an adult Gryllus rubens should have wings extending down its abdomen.
A female cricket would have a long ovipositor protruding from her abdomen, between the cerci., but this cricket does not. Of course the ovipositor might not have developed yet, but I'd expect it to already be protruding a little. Thus I've identified this cricket as a male.

References:
http://bugguide.net/node/view/250789 (Eastern Trilling Crickets/Southeastern Field Crickets)
http://bugguide.net/node/view/8006 (Field Crickets, Genus Gryllus)
http://entnemdept.ufl.edu/walker/buzz/482a.htm
http://entnemdept.ufl.edu/creatures/misc/crickets/grubens.html
http://facstaff.unca.edu/tforrest/ASA%2098%20Seattle/sld028.htm

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