This species is very similar to Drunella flavilinea. In areas where their ranges overlap, they can sometimes be found in the same streams. Allen and Edmunds (1962) say that Drunella coloradensis tends to favor colder water than Drunella flavilinea and that it may emerge as much as a month later.
Where & when
Time of year : July to early October
Preferred waters: Small streams
According to Fred Arbona, this species requires streams which never exceed 60°F, and this limits them to small streams at high altitude.
Specimens of the Mayfly Species Drunella coloradensis