Saturday, February 19, 2011

Jerusalem Crickets

Jerusalem crickets are often imagined to be Near Eastern insects (John the Baptist is often assumed to have eaten the things) but they are not (and he didn't). They only occur in the western half of the United states and through Central America. But if diversity counts as preference (a ridiculous concept for sure) than their favorite place to live must be California. Of the 28 species listed by David Weissman (in his fascinating chapter on their communication and reproductive behavior in Laurence Field's book, The Biology of Wetas, King Crickets, and Their Allies) 19 are from California.

I'm going to call these two crickets Stenopelmatus nigrocapitatus (the dark headed Jerusalem cricket) although I have only a little confidence that this is true. This species is known from Fresno County where I found the second cricket (the first image was from just north of there in Mariposa County). The difficulty is that I don't have a recording of their nuptial drumbeats on which their taxonomy depends. Of course these insects don't beat on drums. In fact they don't even have the typical grasshopper ears (on their side) or washboard sounding mechanism (for rubbing their wings and legs together). But they do drum nonetheless - with their abdomens against the ground. They are also very good at picking up the drumming sound of other Jerusalem crickets with their forelegs.

I found the Mariposa cricket at dusk along the Merced River below Yosemite last November. With flashlight in hand, Jon, Bailey and I had just finished setting up camp and had taken our flashlights to go looking for whatever we might find. It wasn't long before we found the crickets hopping along the dirt road. It's a lot nicer to see these remarkable insects alive than in collections, where they are usually shriveled up and unidentifiable when left on pins. The second picture is of an individual I found three weeks ago along the San Joaquin River north of Fresno. Both insects are about an inch long.

The habitat shot is along the Merced River the day after I found the cricket. It had rained all night and the next day was mostly cloudy. I slept dismally inside the cab of my truck (in which I don't fit horizontally) so that the boys could stay dry in the covered bed. The next day was beautiful nonetheless. November is, after all, a bit of an unpredictable month in these parts. On the one hand it is the end of the year and most living things are asleep or dormant. On the other hand, the rains have begun and grass is starting to grow - a prelude to spring. One sort of takes one's pick on the prevailing mood. And the Merced River somehow knows all of this and tends to speak for itself. By lunchtime I think it was in a good mood.

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