The first instar larvae may be reared from eggs. The larvae are generally cannibalistic. The adults are best studied dry. They may be pinned or pointed after storage in fluids or they may be killed in a killing jar and pinned or pointed directly. The great diversity creates many exceptions for high level taxa.
Most aquatic groups are reasonably well known, taxonomicly as adults at the species level.
The larvae are much less well known. Both stages are poorly known biologically. Mostly a specialist's group below the family level, except for Elmidae. The terrestrial Geadephaga and the aquatic Hydradephaga, mostly predacious with chemical defenses. Haliplidae- crawling water beetles, herbivorous, widespread in ponds and lakes some prefer streams.