>>I suspected tracheal but was unable to detect any under a borrowed scope. 

I wondered about the tracheal mite life cycle...  I think my colonies shed a lot of tracheal mites in the early [cold] spring when weaker bees drop to the ground.  I suspect - can anyone confirm?? - these bees take a lot t. mites with themn since quite a few have the wings at 90 deg. or so to the body.  Do tracheal mites leave older, weaker bees to move onto younger bees?

The colony populations seems to markedly decrease during this time.  Then the populations quickly rebound and the 90 deg. wing orientation becomes hard to find and the colonies do very well for the rest of the season.

Waldemar

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