---

Last week I pinned about twenty flies, mostly calyptrata, from 70% alcohol. Not really having any idea, I laid them on absorbant paper, then pinned them and unstuck the wings. Ten minutes later they looked great and dusting was fine to observe. Three days later they looked awful, the eyes, abdomens and other parts contricted or caved in.

Can this be avoided? It doesn't happen to the Hymenoptera, presumably their integument is thicker??

I looked in Jorges very long thread on pinning, and then did a forum search on 'pinning from alcohol' this netted me 5883 hits, so i thought this might be easier.

Thanks for whatever comments you make,

Gordon

---

It might be better if you bring them out of alcohol gradually, such as a day in 50%, a day in 30 %, then dry them. But that is a lot more work so probably not worth it for routine specimens.

John

---

Critical point drying is probably the best way to avoid collapsing specimens, but requires costly equipment or chemicals. The other technique if freeze-drying (again very expensive equipment) though you could try freezing the specimens immediately after drying. If they are frozen while "plump" and dried in the freezer, they might keep their shape, but I wonder whether it's worth it - if the characters are visible, then don't worry too much about appearance!

---

[quote]John Bratton wrote:
It might be better if you bring them out of alcohol gradually, such as a day in 50%, a day in 30 %, then dry them. But that is a lot more work so probably not worth it for routine specimens.

Do you mean a day in 96%, another day in absolute EthOH? If dehydrated in a liquid, the fly would not collapse, and U can even take pix of it.

Development through ethylacetate ether after 96% alcohol is another good option unless U need your specimens for PCR.

---

Gordon, I have found this method quick and easy: remove fly from alcohol, drain 30 secs on filter paper, Drop in a small jar of acetone (10 ml), leave for 3 hours (vary according to size), remove and immediately pin with short minuten through pleuron under wing base, arrange fly legs and wings under microscope with small pins (I use small block of plastozote 1 inch square), the fly will dry in a few minutes, and can be removed and mounted in a couple of hours. It may be necessary to put a small drop of thinnned seccotine under the fly on the pin to stop it swinging round.

---

OK my thanks to you all, I will experiment with those ideas that don't cost money. LOL I have been wanting a Freeze Dryer for twenty years, but a car and some decent lighting for the microscope and for the camera are miles higher on the list.

Thanks again.

Gordon

---

In reply to Nosferatumyia, three messages back:

I meant take them from the 70% alcohol that they are stored in, through a couple of lower alcohol/higher water media, then dry them. The idea was to rehydrate the muscles or connective tissues that would otherwise distort the fly as they lost their alcohol. I don't know why the drying of hydrated tissues causes less distortion than the drying of alcohol-saturated tissues, but it seems to.

But the other people's suggestions sound much better than mine.

John