THE XERCES SOCIETY FOR INVERTEBRATE CONSERVATION

Aquatic Invertebrates in Pacific Northwest Freshwater Wetlands
An Identification Guide and Educational Resource

The needleflies are medium-sized, long, slender stoneflies that eat leaves and other organic material. Most species in this family live in small, cool streams; some live in seeps and springs.

Leuctridae may be easily mistaken for the Capniidae (snowflies). The character that consistently separates the two families is the pleural folds, which are small indentations on each side of the abdomen used in respiration. Unfortunately, the folds are very difficult to see without good light and may be obscured in small or damaged specimens. If visible, pleura are present only on the first seven or fewer abdominal segments in Leuctrids, and on the first nine abdominal segments in Capniids.

A few additional characters can help separate the two families but they don't work for all taxa. Leuctridae have long parallel-sided abdomens, while many Capniids have a football shaped abdomen, with each segment widest at the posterior edge.