Nosema apis had long been considered to be of concern only in the spring and fall; but once N. ceranae showed up, there are reports of it appearing even in summer.  An understanding of the reasons for the seasonality of Nosema may help us to better understand the parasite as a whole.

Nosema apis was not named until 1909, and was not on U.S. beekeepers' radar until it was well described by G.F. White in his seminal publication in 1919¹. Ingemar Fries reviewed what we knew about N. apis in 1993², and described the typical seasonality of Nosemosis (disease that may be the result of serious infection by Nosema):

The level of infection found in a colony is highly variable. The seasona