Exuviae

Today I returned to the Cannon River to look for emerging clubtails and search for exuviae. Unfortunately a thorough search was out of the question as I had less than a half hour, so I focused on the sandy spit of land upstream of the tributary Spring Creek.

Exuviae are the cast of exoskeletons left behind after dragonflies emerge. Because they are solid, they retain the exact shape of the full grown nymph, a kind of death mask for that previous stage of life. There is a hole in each exuvia located behind the head and between the wing pads where the adult dragonfly made its escape, literally crawling out of itself. The white threads often seen dangling from this exit hole are the tracheal tubes.

There are a number of good reasons to pay attention to exuviae. Presence of exuviae prove the existence of breeding populations. Daily monitoring and collection of exuviae can provide the date for emergence periods and population estimates. Often the exuviae can be identified to species and in some instances can provide records for very elusive adults.

הועלה ב-יוני 7, 2017 03:49 לפנה"צ על ידי scottking