SUMMARYA simple test for diagnosingNosema apisinfections in honey bees, which does not require a microscope, is described. Bee abdomens are crushed in water in plastic 1.5 ml microcentrifuge tubes, nigrosin stain is added and the tube left to stand vertically overnight. Centrifugation of the tubes eliminates the need for an overnight wait. The nigrosin stains any bee tissues and most pollen a dark blue/black and theN. apisspores settle to form a pale grey, unstained pellet at the bottom of the tube. Eight million or more spores per bee can be detected (P<0.05) and the size of the pellet gives an indication of the magnitude of the spore load. Pooled samples of bees crushed in a plastic bag may be similarly assessed, although some accuracy is lost.