Fossil Insects

Over the Christmas break, we had the chance to visit Kathy's sister Linda, her husband Sam (Maestas), and their family. Sam is an amateur paleontologist of the sort that has turned his hobby into his livelihood. He's been telling me for years of his digs and of the interesting dinosaurs and mammals that he has worked with. Growing up in northwestern Colorado he had the opportunity as a teenager to attend a paleontology class given by a local scientist, Les Robinet. Sam was so captivated that he began doing research on his own and volunteered to help with the gentleman in his own digs.



The two became quite close through the years and when Les got too old to manage his small museum and ranch (where many of his fossils were from) he sold them to Sam (my brother-in-law). Since then Sam has worked with a number of scientists and has become very adept at preparing the fossils and has a list of museums around the world that he works with.

Knowing all this, I was a bit surprised when Sam told to me recently that he also had a few fossil insects that had come from a Chinese shipment that he had arranged to prepare. Over the holidays, he invited me over to see a few of his recent pieces that were still in his home. He had a fossil mantis (I think) and a strange fly, although see for yourself. It has strange antennae for a fly. The truth is, I'm not sure what it is. The dragonfly (or damselfly) is also from China. Apparently they're all taken from a level dating back to about 50 million years (to the early Cenozoic Era).

You may run into some of Sam's work in museums around the country. Some of them are also available for sale. You can check out his site on eBay (or you can email Linda directly for more information (lindamaestas@q.com). Somebody who works with insect fossils should get in touch with him.

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.

Phloeodes diabolicus

Ironclad beetles are the tanks of the insect world. They are famous (or infamous) for walking away after being stepped on. There are even reports of species being run over by cars without apparent harm. To an entomologist, they are notorious for the challenge of getting an insect pin through their thick skin (cuticle). What usually happens is the first attempt bends the pin. The second attempt bruises the thumb and forefinger to the bone. And then with a combination of anger and grit (and with two hands gripping the shaft) the pin is forced through the reinforced exoskeleton. With luck it has gone through straight and without popping the legs off on the other side. Very often it doesn't - as verified by any number of oddly pinned specimens stuck to the bottom of unit trays in the museums of the world.



These images are of our most common ironclad beetle in the Central Valley - the diabolical ironclad beetle. How the species got its name is a mystery to me. Perhaps the shiny golden setae on a dark black background in many of the individuals reminded the author (LeConte) of fire and brimstone. Whatever the reason, it is a name (and a species) not easily forgotten.



These images were taken a couple of weeks ago near the King's River outside of Sanger (California). I found a grove of old oaks with one fallen individual cut into bathtub-sized sections. The beetles were congregated under the thick loose bark. They are about three quarters of an inch long and feign death when disturbed - making them easier to photograph. Some of the individuals are completely black and all of them have small velvety black sections on their back. The golden white setae on the shoulders and elytral apex are also very striking - especially under magnification. In the past, entomologists have thought these color differences represented different species. This is hard to maintain when individuals of both patterns are found in the same place (even on the same log as I found here). A full study of this group of ironclad beetles has recently been done by Ian Foley and Mike Ivie (at Montana State University, and published in Zootaxa, 2008). They document a geographical change in this pattern (a cline) and have confirmed that the variability represents only one species.




The habitat shot is along Byrd Slough where I found the little devils.