FUNGOUS DISEASES OF THE HOISTEYBEE 35 



Organisms belonging to the AspergiUv^ fwnigat%i8 group occur on 

 adult bees (pi. 4, A) and less frequently on the brood. Tests for 

 pathogenicity with A. fvmAgatus isolated from bees obtained from 

 widely scattered sections of the United States have all given posi- 

 tive results. Cultures obtained from the collection of Thom and 

 Church and from a prominent drug manufacturer of Detroit have 

 been found capable of parasitizing bees. Negative results have never 

 been obtained with A. fumigatus, but brood-comb cultures placed 

 in colonies caused less damage than was caused by A. flavus. In 

 cage experiments the mortality from the fungus has usually been 100 

 per cent. 



Aspergillus nidnlans occurs less frequently on bees than does A. 

 fvmiigatus. Isolations have been made from adult bees from time to 

 time and once from brood. Inoculation experiments with A. mdu- 

 lans from bees and from other sources seem to indicate that a number 

 of strains are pathogenic to bees. The death rate among bees inocu- 

 lated ^Yith A. nidulans is lower than with A. flavus or A. fumigatus^ 

 and the bees frequently escape infection. 



AsfergUlus glwucws has been isolated from mummified larvae and 

 from adult bees. In experiments with caged bees only a small per- 

 centage were infected, and cultures obtained from the Thom and 

 Church collection failed to attack any of the bees. Brood was not 

 attacked when spores were scattered over larvae from two to four 

 days old. 



The black-spored Aspergillus, Aspergillus niger, has rarely been 

 found on bees, although isolations have been made from adult bees 

 and from mummified larvae, and a few worker bees were attacked 

 in inoculation experiments. Attempts to cause infection of brood 

 by A. niger were not made. Such an extreme case as that described 

 by Morgenthaler {18), in which the comb cells were filled with a 

 loose, dark-brown or black powder and larvae shriveled, but with 

 swollen edges, lay covered with this dust, has never been observed in 

 these experiments. The brood combs of tightly closed hives from 

 which the bees were removed have been observed to be completely 

 overgrown with A. rdger. No noticeable infection occurred, how- 

 ever, when these combs were given to strong colonies even though 

 brood rearing was begun in them within a few days. 



In one instance an organism identified as Aspergillus ochraceus 

 appeared to have been the cause of heavy losses in a Connecticut 

 apiary. Examination of samples sent to the writer showed that 

 more than 75 per cent of the diseased bees were attacked by this 

 organism. (PI. 3, A.) A second lot from the same apiary yielded 

 about 60 per cent of infected bees. Inoculation experiments with 

 young cultures were unsuccessful, as neither bees nor brood were 

 attacked. When year-old cultures that had thoroughly dried were 

 used, all of the inoculated bees were attacked and killed. 



It was found that young but apparently mature spores of this 

 Aspergillus were not only unable to germinate within the alimentary 

 canal but were killed after a short time. No growth occurred after 

 the bees were killed, and the spores failed to germinate when placed 

 on nutrient agar. Gorging with young spores was ineffective in 

 stimulating an attack. During the culture of this organism the 

 spores were observed to be at first thin walled with a gelatinlike 



