As a result of trying out the experts’ industrial-scale collecting technique, that evening I had a full tube of tangled flies to sort through – first of all to pin and then to work out which family they were. Though it wasn’t alwasy necessary, I went through the family key for everything, finding flies in the familiar families of Syrphidae, Keroplatidae, Drymoyzidae, Fanniidae, Mycetophilidae, Scathophagidae, Sciaridae, Opomyzidae, Limoniidae, Dolichopodidae and Lauxanidae. With each journey through the key I became a little more casual, skipping the first 80 couplets when it was obviously an acalypterate. I didn’t even look at the key for the cranefly family Limoniidae, knowing that I had to check that there were two anal veins in the wing, that there were no ocelli, that the eye was bare, that the last segment of the palps was short and that the vein before the anal veins didn’t have a sudden bend in it.
Just as well I was checking, for this fly looked, to me at least, just like a standard Limoniidae – i.e. a small drab cranefly with unmarked wings that I would probably struggle to get to genus and species with. But checking its eyes there was no mistaking the presence of tiny hairs between the facets – giving a silvery halo to the head. At least, that’s how it looked using the binocular microscopes provided for us to use for the Dipterist Forum field trip week – the photos above at low, medium and high magnification show that it’s a bit more of a struggle to see those hairs now I am back home using my own instrument.
This microscope was a present from my Great Aunt, Dorothy Knull who studied Hemiptera, particularly the brightly coloured Cicadellidae or leafhoppers – my microscope is the one in front of her in the photograph, and my computer now sits on that same desk. Her husband Josef Knull was also an entomologist focusing on beetles, and they worked together at Ohio State University from 1934 for the rest of the working lives and on into retirement. Meeting them in Columbus in my early teens was what started me off on insects in the first place. The make of the microscope is Spencer and the serial number 289290 which dates it to 1948. I suppose the optics could now do with a clean – on the highest power the image is especially murky and dusty. My light source is an Ikea reading lamp re-purposed from my eldest son’s bedroom, and could probably be improved upon, although I have to say it is much better than any set up that I have had previously.
Although it feels like an insult to her kindness all those years ago, having now spent a week with a modern instrument in which you can increase the magnification smoothly rather than in big jumps so whatever the size of the fly you can make it fill the screen, its colours brighter, the focus crisper and the lighting more intense, the scales have fallen from my eyes – I had imagined that a new microscope would cost thousands of pounds – but is seems that that is not the case, and it would be nice to see those eye hairs clearly.
The year of the fly 