They feed on many forms of small plant life, both living and dead. They can be found in open water and among masses of waterweeds or algae. The easiest way to collect scuds is to net out a mass of waterweeds or algae and put it into a pan. Then you remove the plants carefully, leaving the scuds and other animals in the pan. Scuds have been seen on snails, tadpoles and even the dead carcass of a water bird.
Scuds are an important food for fish, frogs and birds.
As a food, scuds can be a problem for these animals because they also carry parasites. Scuds sometimes take into their bodies the eggs of tapeworms and other parasites that affect the fish, frogs and birds. The parasites hatch out or stay in egg stage in the scud until eaten by the larger animal. The scud thus passes the dangerous parasite to the larger animal. The scud is thus an 'intermediate host' for the parasite.