338 AMERICAN BEE JOURNAL October 



OBSERVATIONS ON AMERICAN FOULBROOD 



By G. F. White, B. S., Ph. D., M. D., Bureau of Entomology, U. S. Deparlment of Agriculture, Washington, D. C. 



Many beekeepers are driven from 

 the profession and many prospective 

 ones are deterred fiom entering it on 

 account of the losses that result from 

 the bee diseases. As a remedy for 

 this conditron it is proposed that the 

 beekeepers, both active and prospec- 

 tive, become as familiar as possible 

 with the facts which are known about 

 these disorders. 



American foulbrood is responsible 

 for greater losses than any of the 

 other diseases. It has been studied 

 for a considerable number of years 

 and in the present article* are given 

 some of the observations noted, 

 which, it would seem, might be of in- 

 terest to all beekeepers. 



Name of the Disease 



The history of the period before 

 Christ shows that bees at that time 

 died from virulen-t diseases. It is not 

 possible now to determine definitely 

 the number and nature of the bee dis- 

 orders that existed then, but it is 

 quite probable that all of the infec- 

 tious ones of today occurred. By 

 what names they were then known 

 is not clearly recorded. Earlier than 

 three and a half centuries ago a de- 

 structive, foul-smelling brood disease 

 of bees was being referred to as 



"foulbrood." t 



The name "foulbrood" has been ap- 

 plied probably almost from the be- 

 ginning of its use to more than one 

 disease. Numerous descriptions un- 

 der this name occur in the beekeep- 

 ing literature, which emphasize the 

 ropy and foul-smelling symptoms of 

 the disease. American foulbrood, 

 therefore, is one of the diseases 

 which have been described as "foul- 



* Bulletin S09. American foulbrood, U. S. 

 Dept. Agr., March 10, 1920, may be referred 

 to by those who desire a fuller discussion of 

 the work done than is given in this article. 

 The technical parts of the bulletin may easily 

 be omitted by the reader who is interested pri- 

 marily in the more practical portions of it. 



t Colonel H. J. O. Walker, of Lee Ford, 

 England, informs the writer that a German 

 beekeeper, Nicholas Jacob, wrote of foulbrood 

 in a book on beekeeping published in 1568. 



Fig. 2. — Bacillus larvae, growing form. 



brood" and it still is usually meant 

 and interpreted when the term "foul- 

 brood" is used alone. Since there are 

 two especially important and very 

 different "foulbrood," two names 

 were needed to designate them. In 

 the different countries diiTerent 

 names have been chosen and are be- 

 ing used. Probably all of those se- 

 lected are more or less open to criti- 

 cism. The name American foulbrood 

 is being used in this country at the 

 present time for the disease which is 

 characterized by the death of brood 

 in capped cells, ropiness and foul 

 odor, and the name European foul- 

 brood for the one which is not so 

 characterized.* 



Cause of American Foulbrood 

 American foulbrood occurs t least 

 in Belgium, Denmark, England, 

 France, Germany, Switzerland, Aus- 

 tria, New Zealand, Canada, Cuba and 

 in many parts of the United States. 

 From this distribution of the disease 

 it follows naturally that its presence 

 in any locality connot be attributed 



* By employing the names which are being 

 used in this country for these two diseases, the 

 writer is expressing no opinion as to the best 

 ones which have been suggested and used. A 

 previous discussion of names for the foulbroods 

 occurs in an earlier article in the American 

 Bee Journal, July and August, 1920. 



entirely to food or climatic condi- 

 tions. 



No race of honeybees, as far as is 

 known, is entirely immune to the dis- 

 ease. Worker, drone and queen larvae 

 are susceptible to infection; the 

 adult bees are not. 



The inciting cause of the disease is 

 a gerin which is called Bacillus lar- 

 vae. When this parasite is added to 

 honey or .=yrup and fed to a healthy 

 colony the disease is produced (Fig. 

 1). It is a small rod-shaped plant 

 (Fig. 2) that can be seen only by the 

 use of a microscope, and then only 

 when it is magnified 600 diameters or 

 more. It produces spores, which are 

 somewhat like seed (Fig. 3). These 

 spores (Fig. 4) are so small that if 

 20,000 of them were placed end to end, 

 they would measure only about one 

 inch. They live over long periods and 

 are very difficult to destroy, either by 

 heat or chemical disinfectants. 



Fig. .1 — American foulbrood produced experimentally. 



Fig. 3. — Bacillus larvae, spore formation. 



The spores are taken into the stom- 

 ach of the larva with the food. They 

 then germinate, and the growing form 

 of the parasite reaches the blood and 

 other parts of the body. This causes 

 the larva to become sick, and in about 

 one week to die. Sometimes the 

 pupal stage is reached before death 

 takes place. The body of each dead 

 larva and pupa (Fig. 5) contains mil- 

 lions of spores. These are capable of 

 producing the disease should any of 

 them reach healthy larva; and be 

 eaten by them. 



Symptoms of American Foulbrood 



Inasmuch as the practical apiarist is 

 interested in the colony rather than 

 the individual bee, it is well in dis- 

 cussing the symptoms of any bee dis- 

 ease to consider the colony as the 

 unit. Any evidence of disease that is 

 obtained from a larva, pupa or adult 

 bee is, in fact, a colony symptotn. The 

 death of brood or adult bees is fre- 

 quently the first symptom that is 

 noted. In the brood diseases it is 

 only the brood that dies; the adult 

 bees do not even become infected. 



In American foulbrood the brood is 

 almost always capped before it dies. 

 This is due to the fact that the germ 

 does not cause death until one week 

 or more after the feeding larvae con- 



