Gossamer Tapestry

Reflections on conservation, butterflies, and ecology in the nation's heartland

Saturday, January 09, 2010

In which I pretend to be an archaeological entomologist

Shortly before Christmas, I was contacted by everyone's favorite gay archaeologist, Homer. He was working a dig in Tucson and had been uncovering artifacts from the 1890s. One of them was an old can that contained a bunch of dirt mixed with insects. If he sent me a sample, would I be willing to try to identify them? Ever up for a challenge, I said yes. A few days later, a vial of dirt mixed with insect parts arrived. I dug out some equipment and got to work.


The sample contained a bunch of fragments from what appeared to be a fairly large kind of beetle. From the size, color, and location, I had a pretty good idea right away what I was working with. The leg fragments (femora and tibiae only) were the first big clue. The tibia (straight, narrow section above) is about 6.5 mm long and the femur (the more oval secction) is about 7 mm long. They come from a pretty big bug. The metallic green coloring is distinctive. There were what looked like fragments of ribbon of the same color. These were sternites, the ridges of the abdominal segments.


The sample also included a number of oddly shaped plate-like structures that were not metallic green. These were pronota. the pronotum is the dorsal covering of an insect's thorax.


By this point, I was pretty sure that I was working with parts of a biggish scarab beetle called a fig eater (Cotinis mutabilis) . They are bright green with a metallic luster below, and are green and brown with a matte luster above. I have several in my collection, including a couple collected right in Homer's back yard. When I compared the legs and pronota to those on my mounted specimens, they matched beautifully.

Cotinis mirabilis mutabilis
The pronotum is just towards the head from the pin

Cotinis mirabilis mutabilis showing the metallic green underside

Fig eaters range from Texas to California and south into Mexico. In the Tucson area they are a common species and fly from July to September during the summer monsoons. As their name implies, they eat fruit, especially if it's overripe or fermenting. I wonder if they had not entered the can to find fruit or fruit residues inside. Something was probably attracting them to the can, since I found so many remains. I recovered 18 pronota from the sample, which means that there were at least that many beetles in the can at one point.

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At 00:22, Blogger Marvin said...

An archaeological entomologist job well done.

At 01:01, Blogger wcs said...

I wish I had several lives so I could have a go at other fascinating careers. Marine biologist is up there, along with professional tennis player. And thanks to you, I want to add entomologist to the mix.

Ah, life is beautiful but life is cruel!

My word verif is: bowspo. A relative of our favorite psychiatrist in Phoenix, perhaps?

At 03:57, Anonymous Mike said...

Pretty authentic relics you've found. I'll only get to be a wanna-be when you are finally one. :)

At 07:55, Blogger Randy Emmitt said...

Your on your way to being on CSI one of these days. Enjoyed this posting!

At 09:06, Anonymous Sylvia said...

I love these guys - they're big, beautiful and make a satisfactory noise.As a child in Tucson I would catch one and tie a thread around its leg and have a pet on a leash.

Did this container have a lid. Could a child have been collecting them?

At 11:16, Blogger Homer said...

Sylvia- the beetle remains were crammed inside a poorly preserved tin can that lay in a pit containing copper ore waste. The high copper (and probably some other chemicals) helped preserve the remains. I am excited to have Doug as a contributor to my report- the first time we have ever had an entomologist as a co-author!

At 12:43, Blogger Mel said...

Two notes: You wrote the species name as "mirabilis" twice. Also, their range extends all the way to the Atlantic coast.

Growing up in South Carolina, we always called them June bugs. Aside from figs, they particularly loved to feed on deadfall pears in my grandparents' back yard. We would catch them and tie a thread to one of their back legs, then let them fly around at the end of their "leash". As a budding biologist, I loved to watch their brushlike tongues feeding on the soft fruit pulp.

At 13:25, Blogger Doug Taron said...

Marvin- Thanks

Walt- Several of my blogging friends are marrine scientists. I enjoy their blogs a lot.

Mike- I didn't find the artifacts, I only IDed the insect parts. It was fun.

Randy- some years ago I did a radio interview regarding an exhibit at our museum called CSI: Crime Scene Insects. It's archived here. You need RealPlayer to open it. It remains the media interview that I am most pleased with the outcome on.

Sylvia- I agree about the satisfactory noise. I'm glad that Homer showed up and answered the part of your question that I couldn't. I never saw the artifact, only the debris sample.

Homer- Thanks,for the opportunity. It was lots of fun.

Mel- Welcome to the Tapestry. Well, that will show me not to write a blog post too late at night. You are correct, the species name is mutabilis. I just re-checked the report I sent to Homer. Fortunately, I got the name right in the report that I sent to Homer. OTOH, I stand by my account of the species' range. The genus Cotinis does, indeed, range as far east as the Atlantic Coast. The species in the southeast is C. nitida. C. mutabilis is not found east of Texas.

At 13:32, Blogger Doug Taron said...

P.S. Mel, That must have been a lot of sun seeing them feeding on the dropped pears at your grandparents' place. In Arizona one of their favorite non-cultivated foods are prickly pear fruits. I'd love to see the eastern species some time- never have yet.

At 22:29, Blogger Ur-spo said...

I am honored to be bowspo, certainly a next step in evolution or perhaps a convergent evolution?

At 10:42, Blogger Joe said...

Like mel, we called (and still do) these June bugs.

Hey maybe there are that many remains in the can because soembody was picking them off their fig tree to save their fruit! Or to give to their kids to play with.

At 12:23, Anonymous Mark H said...

Wow! I REALLY enjoyed this research project from Dr. Homer to you, Dr. T ! And thanks for sharing it..... I'm always amazed reading how this kind of research work is done...my one brother's a pathologist ....HIS stories are fun too. THANKS for this delightful post!

At 21:13, Anonymous bev said...

This is a rather off-the-wall suggestion for why the beetles were in the can, but... seeing as how I'm here in Bisbee for the winter, a couple of weeks ago, I was poking around through an online history archive for Cochise county. I came across and ended up reading a rather lengthy paper on the miners that worked the copper mines here in Bisbee. Apparently, playing practical jokes on each other was a very important part of "mining culture". Usually, the joke had something to do with lunches, lunch pails, food, etc... Such things as nailing lunch boxes down to boards, removing and replacing the contents of other miner's lunches, and so on, were the standard fare. I can just imagine the mayhem that could be caused with a tin can full of large scarab beetles! (-:

At 18:53, Blogger Kathiesbirds said...

I have seen this beetle (not a bug) in my yard before!


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