296 



STATE BOARD OF AGRICULTURE. 



American foul-brood while still curled up in the bottom of the cell. Combs 

 containing larvae which had died curled up in the bottom of the cell, but 

 which had the coffee color, ropiness and« glue-pot odor of American foul-brood 

 have proved upon microscopical examination to be American foul-brood. 



Fig. 3. Americal foul-brood; a, b, f, normal sealed cells; c, j, sunken cappings, showing perfora- 

 tions; g, sunken cappings not perforated; h, 1, m, n, g, r, larvae alTected by disease; e, i, p, s, scales 

 formed from dried-down larvae; d, o, pupae affected by disease. Three times natural size. From 

 Farmers' Bulletin 442, U. S. Dept. of Agr., Bureau of Entomology. 



No doubt the gross examination of larvae dead in this unusual stage of Amer- 

 ican foul-brood has led to an incorrect diagnosis of European foul-brood in 

 some cases, and has possibly added to the confusion which has existed be- 

 tween the two diseases. 



The scales of American foul-brood are usually uniform in thickness on the 

 bottom of their cells, and as they are removed by the bees with great diffi- 

 culty, it is very seldom that combs containing scales of American foul-brood 

 are cleaned by bees. In all cases which have been brought to the attention 

 of this office where bees have cleaned combs containing scales of American 

 foul-brood, the disease has returned later. 



METHODS OF SPREAD OF THE DISEASE. 



The ordinary medium through which American foul-brood is spread is 

 contaminated honey. Bacillus larvae, the causal organism of the disease, 

 produces spores which are very resistant to all of the common means of 

 control of bacterial diseases, and these spores will live in honey and diseased 

 combs for a period of years. The robbing of diseased colonies by healthy 

 colonies or of empty hives that have contained diseased colonies is the method 



