Paragnetina media Nymphs posses a quite advanced digestive system that includes a stomach.  This enables them to feed on a variety of substances, being mostly other consumers.  They obtain and grind their food by using their strong chewing mandibles on the cephalized portion of their body.  These nymphs are largely carnivorous, secondary consumers mostly feeding on benthic aquatic insects, but are known to consume some vegetable matter as well from time to time.  Adults, however, only survive a few weeks and are herbivores feeding on the grasses located around the streams.   
Some of the main food sources include:


Ephemeroptera- mayfly nymphs, which are mostly prevalent in spring.
Trichoptera- Caddisflies, which are the only food present year round.
Diptera- Dipterous larva
Diatoms- the common food for nymphs during the months of march and April. 
Detrius- Detrius are the smallest contributor to the diet of the nymph. 

(Lehmkuhi 1970)


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