Entomology Collecting at Pawnee Buttes

Pawnee Buttes, Colorado. September 15, 2012.

Today I went on another class field trip to collect insects. This time we went to Pawnee Buttes, part of Pawnee National Grassland. These buttes are remnants of the Brule and Arikaree Formations, relatively soft, fine-grained sedimentary rocks capped by resistant sandstone and conglomerate. The Brule Formation is the same as that in the Badlands of South Dakota, an Oligocene formation deposited between 30 and 34 million years ago. Some parts of Pawnee Buttes contain mammal fossils.

Pawnee Buttes, Colorado

It was fairly dry, but we still saw a good diversity of insects and some other interesting animals. Of course, I forgot an extra camera battery and my battery promptly died, so I was stuck with cell phone pictures the rest of the day, and missed out entirely on a few of the best animals.

The most abundant insects were a great variety of grasshoppers:

Grasshoppers (Order Orthoptera)

We also saw a lot of beetles, mostly darkling beetles (Family Tenebrionidae) and ground beetles (Family Carabidae). Most carabids, including tiger beetles, are predators. Tenebrionids like this one are often scavengers (you can also see an ant feeding on the grasshopper leg):

Scavengers

My favorite animal of the day was a velvet ant mimic jumping spider, likely Phidippus johnsoni, but alas, no pictures. (Nor any of velvet ants–I brought one home to put in a terrarium, but so far she is hiding).

But after the jumping spider, my other favorite animal of the day were the abundant Greater Short-horned Lizards (Phrynosoma hernandesi) we saw as we were heading back. These are a type of “horny toad,” perhaps best known for the ability of some species to eject blood from their eyes as a defense, primarily against canine predators. We saw one very tiny baby:

Greater Short-horned Lizard (Phrynosoma hernandesi)

With impressive camouflage:

Greater Short-horned Lizard (Phrynosoma hernandesi)

And several larger individuals, including this one:

Greater Short-horned Lizard (Phrynosoma hernandesi)

Despite the dryness, it was a pretty good day of collecting, and we all added some interesting insects to our collections.

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