Several species of mites can be found on the wings or body of dragonflies and damselflies. On a movie of Ischnura elegans some twenty mites can be seen on the underside of the abdomen. Watching this recording together with Marcel Wasscher lead to interesting questions. It is remarkable how vehemently the damselfly tries to remove the mites. It is easy to imagine how this damselfly feels the mites and than comes into action -- but the question is: does a damselfly feel something or not? Isn't using the word 'feeling' an anthropomorphism?
You can see it for yourself on three short shots out of the 17 seconds of combing the abdomen. I did not compress the movies strongly, so they are rather big and you can see all details (but I give half-size versions too). They are best viewed using Quicktime, which makes it possible to go back and forth one frame with your arrow-keys. (Quicktime for windows or Mac can be downloaded free.) The film plays at half speed, frames are .02 seconds apart
I thought damselflies clean their abdomen by combing it between two legs. Here you can see that they sometimes use one underleg (2 seconds, 1.6 Mb) or one foot (1.2 Mb) or two legs (0.8 Mb). (Click for compressed versions: A (600 Kb), B (360 Kb), C (280 Kb).) She firmly places her leg on the mites and presses until the leg is released with a shock.
How does the damselfly perceive that something is wrong? Visual by inspecting the underside of the abdomen at the start of combing it? Tactile after starting the combing? Or by really feeling those nasty mites? In all three cases damselflies should have some 'idea' of what is normal and what is not, I think. I am very curious about hypotheses/conclusions of specialists who see these movies.
This female Ischnura elegans has been recorded in the eastern part of the Netherlands. I was there with Tieneke de Groot videoing for a movie with 'all' Dutch Odonata, in 'all' their forms and showing 'all' kinds of behaviour. Of course 'all' is hard to obtain, but march 2006 a DVD is releases version with 61 of our 71 species. You can find a Dutch text about it on here, an English translation will follow. (The DVD costs € 14,95 without shipping.)
Weia Reinboud (weialibel (at-symbol) xmsnet (dot) nl) (See my index page in case it is not yet open.)