The Pacific and Plains Forktails have a wide distribution in Arizona and can be locally abundant. Mature males of both species are easily identified by the color of their thorax (front: black; sides: blue) and two pairs of blue dots on the front of the thorax. Separating the two species, however, requires close examination of the thorax and appendages.
Pacific and Plains Forktails
-
Ischnura cervula -
Ischnura damula
Male Comparison
Thorax
- Pacific Forktail: Thorax dark above and with two pairs of blue dots.
- Plains Forktail: Similar to Pacific Forktail, but in addition males generally have a thin blue line on each mesostigmal plates - see picture below.
Appendages
- Pacific Forktail: conspicuous forked dorsoapical projection on segment 10; relatively small cerci; paraproct tips straight;
- Plains Forktail: small (compared to Pacific Forktail) dorsoapical projection on segment 10; large cerci; paraprocts tips distinctly curved upward.
