Stream Bluet, Enallagma exsulans 1.1 - 1.5 inches in length. ..

The Stream Bluet is the most common bluet found at running waters in the Northeast. The male is a black-type bluet (abdomen pattern is mostly black). The female has a greenish thorax, black abdomen with a blue tip. Field identifiable.

 
 
Male has blue abdominal rings but only segment 9 is completely blue on top.
 
 

Mature female has sides of thorax green and narrow green shoulder stripes. The wide black shoulder stripe is often divided by brown. The abdomen is mostly black above with segments 10 and most of 9 blue.

Similar species: Most other female bluets that have dark abdomens with blue tips also have blue thoraxes. Vesper Bluet (E. vesperum) female usually has a brighter green thorax, narrow shoulder stripes, and is more slender. Southern Stream Bluet females can be bluish and be confused with female Blackwater Bluets. Male forktails (Ischnura) have segment 10 dark above.