Spores of Nosema apis, stored in water and refrigerated at 40[degree]F., retained their viability for at least 6 years and 7 months. Different amounts of these spores were fed in sugar sirup and water to healthy caged honey bees (Apis mellifera) in 7 consecutive years. Within 7 days after the death of the 1st infected bee, the remaining dead bees in the inoculated cages showed 100% infection. Uninoculated sister bees remained uninfected. The average longevity of inoculated bees was 11 to 27 days less than the controls.