The Stream Doctor

March 24th, 2003

Email YOUR Questions directly to the Stream Doctor. This is your opportunity to get an experts professional opinion on anything stream related.

Q. I am the river management officer for my local club in Scotland, the Avon Angling Club. We need to catch larva and flies from the river for study and would also like to display them as we have different organizations visit our club house. What's the best way to display the larvae and how do we mount the flies? Thank you.

A. Aquatic insects are usually stored in liquid preservatives in museum collections, although I suppose it would be possible to mount some adults on pins as they do with terrestrial insects. Pinned adults usually retain their original colors better than preserved specimens; they are, however, very fragile.

One recommended preservative for adults is a mixture of 80% ethyl alcohol with 1% Ionol (an antioxidant) added. The most common preservative for immatures is 95% ethyl alcohol. However, other fluids are sometimes preferred. One such is modified Carnoy fluid (glacial acetic acid, 10%; 95% ethanol, 60%; chloroform, 30%). This is good for initial field collecting. Within 24 hrs, the Carnoy fluid is drained and replaced with 80% alcohol. An excellent substitute for Carnoy fluid is Kahle's fluid (formalin, 11%; 95% ethanol, 28%; glacial acetic acid, 2%; water, 59% - to be added in the field). Kahle's fluid should also be drained and replaced with 80% alcohol within a week of field collecting.

Glass vials are the most common containers in which to exhibit and store preserved aquatic insects.

~ C. E. (Bert) Cushing, aka Streamdoctor
105 W. Cherokee Dr.
Estes Park, CO 80517
Phone: 970-577-1584

The 'Stream Doctor' is a retired professional stream ecologist and author, now living in the West and spending way too much time fly-fishing. You are invited to submit questions relating to anything stream related directly to him for use in this Q & A Feature at

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