Tuesday, May 31, 2011

Sierran Treefrog

On the same trip that I found the Scaphinotus ground beetle (see previous post) I came upon a stream less than a mile further up the hill. I was a bit surprised that there was as much water as there was. For even though this is the foothills of the Sierra Nevada, this particular drainage is fairly low - just the back side of Table Mountain, a low elevation plateau.

I was even more surprised to hear many frog calls and went in for a closer look. I spent several minutes (it seemed a lot longer) looking for the creatures but couldn't find a single one and as I approached the water their calling stopped. How hard could it be to find a frog when I knew there had to be several of them there?

Finally I spotted a little movement in the water and there they were - perfectly quiet and holding on to small rocks in the slight current. I'm not a frog expert by any means so I had to dig out the field guide for an identification. I think it fits pretty well with the description of the Sierran treefrog Pseudacris sierra. It's quite an attractive animal and a bit unusual in that for a treefrog it was obviously adapted here for life on the ground. Of course, the Sierra foothills are quite dry most of the year so this makes sense. I'm not really certain though that the stream even runs all year. I may go back in September and take a look.

Saturday, May 21, 2011

Scaphinotus subtilis

Snail eating ground beetles are some of the most fascinating insects around. They have a rounded body with a narrow head and prothorax that gives them a fairly sleek appearance. I'll be honest though, I've never learned just how this particular morphology benefits them. I invite anybody reading this post to inform me if they happen to know. Part of the uncertainty is why the wide abdomen is mostly filled with air.

This beetle (Scaphinotus subtilis) is the most common snail eating carabid around Fresno. It has fairly smooth wing covers and is a bit smaller than some of the other Scaphinotus but it is still an impressive creature.

I found this one on the back side of Table Mountain (northeast of Fresno) in February. It was under the logs seen here along with several isopods and various other edaphic creatures.

Tuesday, May 10, 2011

Limonius crotchii

This is the first individual of Limonius crotchii that I have ever seen alive. It is not a very commonly seen insect. Jon and I came across it a couple of weeks ago just north of Lake Isabella along the North Fork of the Kern River (just into Tulare County, California). The orange elytra are quite striking and are a lot brighter than in preserved specimens.

It isn't all that big - just about a half inch long (over a centimeter) and it does look similar to other black and orange elaterids. Species of Ampedus can often look similar and even have the double sutures on the prosternum (on the underside of the pronotum). Even the front of the head in L. crotchii looks more like Ampedus than some other Limonius.

A good way to distinguish this beetle, though, is to look at the base of the front legs which are nearly completely closed (meaning they are surrounded by the hypomera). If this sounds all too complex, you can simply take my word for it (fortunately I'm only wrong less than half the time :).

It has been a wet year in many parts of California and the North Fork was very high. We saw several brave river rats floating rapidly along in bright red rafts. The habitat shot is just off the road from the river near an unmarked camping area where we stayed.