A. The most commonly used preservative for aquatic insects is 80% ethanol. This does a pretty good job for long-term storage, although some folks add 1% Ionol, an antioxidant that helps preserve color.

Another preservative widely used by aquatic insect collectors is Kahle's fluid. It is made up of ethyl alcohol (15 parts by volume), formalin (6 parts), glacial acetic acid (1 part), and distilled water (30 parts). The benefit of Kahle's fluid is that it penetrates tissues rapidly before decomposition begins, kills quickly, and preserves color well. However, the Kahle's fluid should be drained before permanent storage in 80% ethanol.

All-in-all, I'd recommend sticking with 80% ethanol.