Friday, February 11, 2005

My Ph.D. advisor said many memorable things to me over the years, but the one that's most pertinent to my life right now was addressed to his entire Entomology class in the fall of 1992, when I was a master's student in another professor's lab. We had first learned to key out adults of all the orders of insects, and then the major families of most orders, and we ended with perhaps the most challenging order of all, the Diptera. "You are finally reduced," Dave told the class, "to counting the hairs on a fly's leg."

I got an A in Dave's class (my term paper and exams brought up my otherwise mediocre collection grade), but was never especially speedy with a dissecting microscope, and have not done any serious collecting since another taxonomy class I took a few years later. Over the past couple of years I've tried to take up ant collecting, but once I built up a stock of samples in vials I realized that I was going to have to move them soon -- and pinned specimens, though excellent for ID work, are fragile. So even my beloved ants are still waiting in my basement, soaking in alcohol in glass vials.

And, I also have to admit, if there was one order that always inspired me to new depths of avoidant behavior in Dave's class, it was the Diptera. Count the hairs, hell -- I couldn't even see most of them. I figured my much easier Hemiptera (true bugs) and Odonata (dragonflies) would get me through, and on Dave's point system for collections, they did. The only other time I had to deal with Diptera was in an Immatures class at Michigan State. After that class's horrifying initiatory roadkill-and-cowpie rite, I became passable at keying out fly larvae, but after you've looked up enough maggot butts, you either surrender to the lure of forensic entomology or else skedaddle off into something more genteel, like population genetics. I chose the latter course.

Karma will out. Not only am I now working in a Drosophila-oriented lab in a Drosophila-heavy department, but I'm the one person there whose current project requires taxonomic skills. The microscopes there are much, much better than any of the ones I've ever used in classrooms, but it's still a slow process for me to identify previously collected flies. There's no choice but to slog through this part, though, because by spring, I'll have to be ready to dive into a major effort that combines fieldwork, taxonomic identification, extensive genotyping, data analysis, and specimen management. (We are not talking about long-captive Drosophila melanogaster, the six-legged lab rat, here. We're talking about free-range Drosophila of many different species; tough-talking, hard-flying critters that lay eggs on poisonous mushrooms and fight hordes of voracious nematodes for their food. Also, there are flies in these communities that don't belong to the genus Drosophila at all. In fact, the mushroom communities also include wasps, beetles, spiders, and Flik only knows what else.)

The flies have hairs on their legs, and their heads, and other parts of their bodies that have no human counterpart. They're not called just "hairs", either. The flies have vibrissae and setae and postverticals and bristles and all sorts of things that stick out. I've counted a few.

And I met a little Drosophila today whose bristles I didn't count. She'd emerged from her pupa with an odd malformation -- a double set of genitalia. Other than that, she seemed healthy though slow-moving. One of my labmates isolated her in a glass vial and handed her to me for a look. "Is it a mutation that affects segmentation?" I asked. "Naaah," my labmate smiled. "She's just a freak."

Like all the other Drosophila I've met, she was a cute little bug. And, despite her developmental anomaly, alive. My favorite kind.

1 Comments:

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