FUNGOUS DISEASES OF THE HONEYBEE 19 



When dead bees infected by aspergillus are kept in a moisture- 

 saturated atmosphere at ordinary temperatures the fungous growth 

 continues after death and attacks all of the softer tissues of the 

 abdomen, thorax, and even the head. Tufts of mycelium and coni- 

 diophores develop at the body openings. Conidiophores also grow 

 through the thinner parts of the exoskeleton, at the articulation of 

 the body appendages, and at the junction of the abdominal segments. 

 (Pis. 3, A and B; 4, A; and 5, A.) When conidiophores do not de- 

 velop upon the surface of the dead bees they may do so inside the 

 exoskeleton of the abdomen or thorax. (Pis. 4, B, and 5, 1^) 

 Conidiophores do not develop in a very dry atmosphere, whereas an 

 excess of water aids the growth of bacteria and thus prevents the 

 development of conidiophores. 



After inoculation and before symptoms of mycosis have appeared 

 the spores present within the alimentary canal increase in size as 

 a result of imbibition of water, except within the honey stomach, 

 where the contents are usually highly concentrated. When several 

 times their original size the spores germinate, and an extensive 

 mycelium develops. (PI. 6.) Spores that germinate within the 

 ventriculus may limit their growth for a time to the food contents, 

 but the wall is soon penetrated by the developing mycelium. A simi- 

 lar process of development may ocbur within the pharnyx, proven- 

 triculus, small intestine, or rectum, and less frequently within the 

 honey stomach. The Malpighian tubules usually remain free from 

 attack until after the death of the bee. The trachea likewise remain 

 free from attack, even in advanced stages of decay after death. 

 Spores appear to be unable to germinate within the trachea, owing 

 to dryness resulting from aeration. In addition, these organs are 

 protected from perforation by the tough layers of the interior sur- 

 face. The small quantity of available food-supplying material 

 within the tracheal walls likewise limits fungous growth. All of 

 the softer tissues of the three divisions of the body may be attacked 

 by the fungous mycelium. The thoracic muscles are a favorable 

 medium for the development of pathogenic species of Aspergillus. 



The infection of adult bees with pathogenic fungi results normally 

 only from the germination of spores within the alimentary canal. 

 Spores failed to cause infection when placed on various parts of the 

 exterior body surface of adult bees, and germ tubes from spores cul- 

 tured in small quantities of nutrient media did not penetrate the 

 tissues when placed on the soft covering of the neck or in the folds 

 of the abdominal segments. Spores spread over the openings of the 

 spiracles likewise failed to cause infection. 



Symptoms of Mycosis in the Beood 



In brood, as with adult bees, Aspergillus infection shows a number 

 of more or less arbitrary stages, depending upon the degree of devel- 

 opment of the infecting fungus. The changes ip symptoms may 

 occur with considerable rapidity within a periofl of a few days owing 

 to the rapid growth of mycelium. Both larvae and pupae are at- 

 tacked by any of several common species, but after the feeding state, 

 and especially after the cells are capped, the chances of infection are 

 considerably reduced. In these experiments the larvae were attacked 



