Thread subject: :: Pinning flies and wasps and some curious questions.

Posted by ChrisR on 04-10-2007 16:54

The way people arrange a specimen when it is pinned is largely dependent on the way the insect is identified. Lepidopterists mainly use wing pattern so it's important to arrange the wings so all 4 are visible. With Diptera it isn't so important to pin them like that and in fact I prefer specimen side-pinned with wings at 45-degrees so that areas under the wings (the legs and pleurae) are also clearly visible.

How do you hold the flies when pinning not to break bristles etc? They are generally quite fragile, I believe.

Flies are quite soft and floppy until they have dried so any pinning and arranging must happen while they are soft and pliable. In a relaxed state they can be handled easily with pointed forceps. Once pinned the specimen is always held using the pin.

How do you arrange the legs and wings in the right position? I think lepidopterists use (rice) paper to pin down the wings when drying.

I side-pin into a sheet of foam and if anything needs holding (not wings - usually genitalia or legs) I use more small pins, crossed to hold the parts firmly.

How do you know what pin size to use? Are there a rule of thumb for this?

In general you should use the largest diameter pin you can without damaging the specimen (within reason). It is a thing you learn with experience and by seeing other specimen collections though. My advice is to go to a museum and ask to see their collections.

If killed in alcohol. Can the flies be pinned directly or do they need to be dried first? ... or maybe you never pin flies that have been in liquid?

Flies out of alcohol tend to be fairly floppy but stiffer than if freshly caught. The worst thing with alcohol is that the genitalia are usually locked fairly tightly and when the alcohol evapourates some soft-bodied flies can dehydrate and crumple. I am lucky because tachinids don't usually have this problem so they would just need to lay on some paper for a few minutes to drain away most of the alcohol and then thay can be pinned. :)

Chris R.