Nemouridae is a family of stoneflies

Plecoptera

Plecoptera are an order of insects, commonly known as stoneflies. There are some 3,500 described species worldwide, with new species still being discovered. Stoneflies are found worldwide, except Antarctica...

. This is one of the largest stonefly families with more than 600 described species with a mainly Holarctic

Holarctic

The Holarctic ecozone refers to the habitats found throughout the northern continents of the world as a whole. This region is divided into the Palearctic, consisting of Northern Africa and all of Eurasia, with the exception of Southeast Asia and the Indian subcontinent, and the Nearctic,...

 distribution. Members of this family are commonly known as spring stoneflies or brown stoneflies. Fly fishermen

Fly fishing

Fly fishing is an angling method in which an artificial 'fly' is used to catch fish. The fly is cast using a fly rod, reel, and specialized weighted line. Casting a nearly weightless fly or 'lure' requires casting techniques significantly different from other forms of casting...

 often refer to these insects as tiny winter blacks.

Although these insects utilize a wide range of flowing water habitats, they tend to be most prevalent in smaller streams. The nymphs

Nymph (biology)

In biology, a nymph is the immature form of some invertebrates, particularly insects, which undergoes gradual metamorphosis before reaching its adult stage. Unlike a typical larva, a nymph's overall form already resembles that of the adult. In addition, while a nymph moults it never enters a...

are distinctive, being broad-bodied and bristly with divergent wing-pads.