When a specimen has become oily (Lepidoptera, Coleoptera, Orthoptera, etc.,) use a bottle with a neck wide enough to let the specimen slip through easily, pin and all. Put in this bottle enough common naptha to fully cover the insect, and introduce it into the fluid. Leave it in the bottle from 10–12 hours. Then take it out, and lay it on some blotting paper, where it will soon dry. If not yet clean, introduce in fresh naphtha once more.