Posted by jorgemotalmeida on 23-10-2007 17:39
#36
Tony Irwin wrote:
Adrian wrote:I have to take slight (but not pedantic) issue with your view that dry material is always better for long term storage. Sometimes it is, sometimes it isn't. I wouldn't keep a cecidomyiid on a pin but would keep a syrphid that way.
I think the main argument against long-term storage in alcohol is that without adequate fixing, and carefully controlled concentrations, the material will eventually disarticulate. I agree completely with what you say about damage to dry specimens (not to mention the dreaded
Anthrenus! :() but I do find that a dry reference collection is much easier to work with - I can line up half a dozen specimens of closely related species and compare them directly - they are never separated from their data or determination labels, so never go back in the wrong place - not so easy to accomplish with specimens out of tubes! I wouldn't pin a cecidomyid, or a sciarid, or a phorid, but I would slide-mount them for examination and long-term storage. But then I need to decide what mountant to use (but that's another thread! :))
As a matter of fact, I think Cecidomyid should never pinned... they are so fragile! I put always these flies in ethanol 70% (i need to get some glicerin as well... I use this thumb's rule: 1 drop of glicerin for small, very small flies; 2 drops for medium flies and 3-4 drops for the big ones in a small vial (1 cm diameter, about 4 cm lenght.)
Hopefully this weekend I will show the vials I use. The big problem is that it is not easy to see the specimens through the plastic surface... but the vials have good quality. And we can buy 1000 vials for 45 euros....
I use vegetal paper inside the vial with data (written in pencil, of course) and it works very well! The data are well visible in spite of being a plastic surface... :) I put the label outside the vial on the cap (?) and surrounding the plastic surface at least 1/4 of the vial.
Edited by jorgemotalmeida on 23-10-2007 17:44