The Society for the study of flies (Diptera)

Affiliated to the British Entomological and Natural History Society (BENHS)

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#1 2018-04-06 17:11:21

batch valley wildlife
DF Members
Name: Mike Shurmer
From: Shropshire VC40
Registered: 2015-02-20
Posts: 32

Processing Pan Trap samples

Hi all

I have a project this year, part of which is using water (pan) traps for sampling Diptera. I am intending to place specimens in 70% IMS for subsequent identification to at least family level.

I was wondering if anyone with experience of this could suggest the best means of processing the specimens at the microscope, in terms of whether it is best to keep specimens wet or best ways of drying out to help with identification.

Many thanks




#2 2018-04-07 22:11:33

DF Members
Name: Nigel Jones
From: Shrewsbury
Registered: 2008-02-27
Posts: 701

Re: Processing Pan Trap samples

I just pick flies out of the IMS and put them onto paper towels, then gently dab them and move them around on the towel. Then leave them to dry for a while, following which they are easy enough to pin. To save time I don't pin most of them, but try to ID them unpinned.

Nigel Jones



#3 2018-05-06 01:40:24

DF Members
Name: Barbara Ismay
Registered: 2008-02-14
Posts: 135

Re: Processing Pan Trap samples

We used to sort them in sub-set in a cut down margarine pot (with a flat bottom) and then sort those of interest or that needed closer looking at into small dye glass blocks. Taking them out onto paper towel could dry out some of the small specimens or damage them. Tachinids you can easily pin, then blob onto a bit of tissue, blow from behind (to unfold the wings) and let them dry. Apparently that works for some other larger calyptrates as well. Dolichopodidae will usually have collapsed eyes, even if you recover them carefully. Many acalyptrates will shrivel, but you can recover them from alcohol by pinning them first, the leaving the specimen in a small tube overnight in 2-ethoxyethanol overnight, and then for a short while (a few hours) in ethyle acetate. You cannot dissect these afterwards as the process makes them britle. If you have the glass blocks (dye or watch glass) then you can use a swan-neck lamp to get light into this from two sides - that way you can see the dusting on the specimen in alcohol.
Hope this helps.
Good luck,



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