Question

Почему поденки не питаются во взрослом состоянии?

Answer 1

А зачем? Они живут очень-очень мало. Единственная функция имаго (взрослой особи) - размножение и расселение. 

Answer 2

Why don't mayflies feed in their adult stage?

Mayflies, also known as Ephemeroptera, do not feed in their adult stage. This is because adult mayflies have vestigial or non-functional mouthparts, which prevent them from feeding. Instead, their sole purpose as adults is to reproduce. The adult mayflies only live for a short period, usually from a few hours to a few days, during which they mate and lay eggs before dying.

This unique life cycle of mayflies, with a non-feeding adult stage, is a characteristic feature of their biology. The lack of functional mouthparts in adult mayflies is a result of their evolutionary adaptation to their specific ecological niche and life history strategy.

In summary, mayflies do not feed in their adult stage due to the vestigial or non-functional nature of their mouthparts, which limits their ability to consume food. Instead, their adult stage is primarily dedicated to reproduction, and they have a short lifespan as adults, typically living for only a few hours to a few days