Check varroa level
To find out if the colony needs to be treated, count the number of dead mites on the bottom board over 7 to 10 days.
In the spring: If you find more than an average of 1 mite per day you should consider treating the colony.
In the fall: If you find more than 15 mites per day, you should consider treating the colony.
PICTURES JAOCHIM of a varroa mite, of the bottomboard of lars checking his clean board.