I recently went to visit my friends Andrew and Janet, who live across the valley from here. They are expert naturalists and amongst the many useful things they do is to identify and record various insect groups. Their latest passion is fungus gnats. These are small, grey-brown, flies typically 2-3 mm long, whose grub-like larvae feed on fungi and various kinds of plant material. There are probably several hundred species in the UK but nobody is quite sure. There is much we don’t know about fungus gnats.
In most respects fungus gnats are very similar but, for reasons that are hard to fathom, natural selection has caused the males to evolve remarkably varied and elaborately structured genitalia, which are different between each species. Consequently if you want to know which one of these very small insects you have found you must look at the details of their genitals. The only way you can do that is to dissect these out from a dead insect under a microscope. As you can probably imagine dissection at that scale is a skilful and very precise business – and that is Andrew’s job.
You may not be surprised to know that fungus gnat specialists are few and far between and if you need to consult and collaborate with others they need to be able to see what you can see down the microscope. This is where the second part of the process comes in – and it is Janet’s specialism. She has developed a way of photographing the dissected-out genitalia which are under the microscope. A special camera is fitted to the top of the microscope and linked to a computer monitor on which the image is projected. This is then used to very precisely guide the photography fractions of a millimetre at a time, painstakingly tracking both laterally and into the depth of the image on the screen, gradually stacking hundreds of photographs one on top of the other to produce a composite image. The results are surprisingly beautiful – like exquisite drawings of something mysteriously ‘other’, clearly organic but hard to place.
All of this seems to raise two questions: why would anyone want to photograph the genitals of a fungus gnat and who cares about them anyway? The answer to the first question is that the photographs (and previously drawings) are the way we can share and extend our knowledge of the identification and distribution of these, admittedly obscure, insects. And the answer to the second question is that ecologists frequently tell us that the ecosystems on which we all rely are determined by an interlocking dependence of millions of species, from microscopic single-celled creatures up to elephants and humans. If you start to lose components of that almost infinitely complex web it will eventually begin to malfunction and ultimately collapse. These are literally our life support systems. Consequently fungus gnats matter because everything matters scientifically – and some would say metaphysically. If we don’t understand what we have got we can’t know when and how we are doing damage to those complicated life webs. What Andrew and Janet are doing is part of a painstaking, committed and largely unsung process that has advanced human knowledge and understanding of our world over centuries. Slowly and patiently inching forward.
photographs: janet grahem