tokens: The common orders of insects that are found in river ecosystems include Ephemeroptera ( also known as a mayfly ) , Trichoptera ( also known as a caddisfly ) , Plecoptera ( also known as a stonefly , Diptera ( also known as a true fly ) , some types of Coleoptera ( also known as a beetle ) , Odonata ( the group that includes the dragonfly and the damselfly ) , and some types of Hemiptera ( also known as true bugs ) .