The passage of viable algae and protozoa through digestive tracts of field-collected herbivorous and carnivorous aquatic insects was demonstrated. Thirty-two genera of viable algae and protozoa were identified from 36 cultures inoculated with aquatic Hydrophilidae hindguts; 86% of the beetle cultures yielded organisms. Nineteen genera of algae and protozoa were identified from 107 cultures inoculated with dragonfly feces; 65% of the dragonfly cultures yielded organisms. The results indicated that herbivorous aquatic beetles were more important than carnivorous dragonflies in dispersal of algae and protozoa by passive internal transport. The results were ecologically significant since aquatic insects periodically disperse, carrying a variety of aquatic microorganisms adapted for alimentary survival during overland transport. Not only was internal transport of spores, cysts, and resistant structures possible, but transport of vegetative algal cells also was demonstrated.