1920 



AMERICAN BEE JOURNAL 



267 



Fig. 9. Stomach contents removed from larva sick of European foulbrood 



indeed is comparatively sliglit. 

 Should they get into the water supply 

 of the bees a possible means for the 

 transmission of the disease would be 

 supplied. The chances would be in- 

 creased if the body oi water is near 

 the apiary, and is a slowly changing 

 one. A colony being weakened by 

 disease becomes a prey for robbers, 

 and at once becomes the source of 

 infection for other colonies of the 

 apiary, and at times, also, for other 

 apiaries. The likelihood of the dis- 

 ease being transmitted by extracted 

 'honey has been overestimated at 

 times. 



Brood-combs containing brood 

 dead of European foulbrood will 

 transmit the disease by being placed 

 in a healthy colony after being stored 

 over winter at room temperature. 

 The maximum period they will do so 

 has not been determined. Hives tha; 

 have housed European foulbrood 

 colonies do not seem to be a likely 

 source of infection. Hive tools and 

 the hands or clothing of the api- 

 arist are not to be feared as sources 

 of infection. 



Since all of the colonies of the ex- 

 perimental apiary were in the open, 

 the bees having free access to flight, 

 and no spread of the disease from 

 colony to colony was observed, it is 

 evident that the flowers visited by 

 bees from diseased colonies and af- 

 terward by those from healthy ones 

 are not a fruitful source of infection. 

 The observation serves to show also 

 that the water supply (no slowly 

 changing body of water was near 

 by) of the bees did not endanger the 

 healthy colonies of the apiary. Since 

 there was no spread of the disease 

 observed, a drifting of bees or the 

 wandering of drones as might have 

 have occurred did not result in any 

 appreciable infection. The observa- 

 tions made during the experiments 

 do not indicate that the disease is 

 likely to be transmitted through the 

 medium of queens. 



Diagnosis of European Foulbrood 



The death of brood in uncapped 

 cells, the yellow color of larvae re- 

 cently dead, the brownish hue of 

 those longer dead, the irregularity of 

 the brood and the absence of the 

 foulbrood odor are symptoms of Eu- 

 ropean foulbrood by which the bee- 

 keeper, after a little experience, can 

 diagnose readily, and at the apiary, 

 most cases of the disease. 



Both late and early in the course 

 oi the disease, however, the diagno- 

 sis is frequently not so easy. Late 

 in the disease the bees may have re- 

 moved most or all of the dead larvx 

 from the uncapped cells and some of 

 those from the capped ones, leaving 

 only the larger scales that occupy 

 the endwise position in the cell. The 

 number of such scales in a given area 



of brood-comb, however, is small. 

 While these scales resemble individ- 

 ually those of American foulbrood, 

 they are fewer in number, and when 

 dry are morp easily removed. When 

 dry, also, they are more rubberlike* 

 in consistency than are those of the 

 ropy disease. From the gross ap- 

 pearance alone the diagnosis can fre- 

 quently be made of these cases. In 

 the laboratory it can always be made 

 readily and easily from a suitable 

 sample.f 



In European foulbrood a larva, be- 

 fore it dies, manifests symptoms by 

 which an early diagnosis may be 

 made.t A pronounced wavelike movc- 



* The word "rubberlike,'* used in this con- 

 nection does not imply that the scales can be 

 stretched like a rubber band, but siir.jily that 

 when dry they are less brittle than those of 

 American foulbrood. The scales of both dis- 

 eases when in a moist environment (a sample 

 enclosed in a tight box, much moisture within 

 the bive, or even on a very damp day) take 

 up moisture readily and become soft. Under 

 such circumstances, therefore, neither the term 

 "rubberlike" nor "brittle" would be applicable 

 for the scales of either disease. 



f McCray and White. The diagnosis of bee 

 diseases by laboratory methods. U. S. Dept. 

 Agr., Bur. Ent. June 21, 1918. 



The diagnosis of European foulbrood in the 

 laboratory from samples received from bee- 

 keepers is usually made, or is at least con- 

 firmed, by finding Bacillus alvei in the dead 

 brood. This procedure has been adopted be- 

 cause Bacillus alvei is readily recognized in 

 making an examination of the samples, while 

 Bacillus pluton is not, and the method is made 

 possible from the fact that Bacillus alvei rarely 

 occurs in other bee diseases, and when encoun- 

 tered in them is found in very small numbers 

 only. The diagnosis in experimental studies, 

 on the other hand, is made, aa a rule, from the 

 presence of Bacillus plnton in the living but 

 sick larvae. A few facts in connection with the 

 disease make this difference in methods readily 

 understood. 



Bacillus pluton, the cause of European foul- 

 brood, is present in large numbers in the stom- 

 achs of larvs sick but not yet dead of the dis- 

 ease, while Bacillus alvei, if present at all, oc- 

 curs then in small numbers only. In experi- 

 mental studies an early diagnosis is especially 

 desired. Sick larvs, rather than dead ones, 

 are used and Bacillus plulon is naturally the 

 germ that is looked for. 



As the brood in samples received from the 

 beekeepers usually dies before reaching the 

 laboratory, naturally the diagnosis from such 

 samples must oe made from dead larvae. The 

 bacterial finding in the dead larvx is usually 

 quite different from that of the sick ones. 

 When the larva: die Bacillus pluton stops grow- 

 ing, but Bacillus alvei begins to multiply then 

 at a very rapid pace and invades the entire 

 larval remains. Upon examining such larva:, 

 therefore. Bacillus alvei is encountered in very 

 large numbers, while Bacillus pluton. in com- 

 parison, is present in small numbers only. 

 While all larvx dead of European foulbrood 

 do not contain Bacillus alvei. the brownish and 

 somewhat viscid ones, the scales resulting from 

 them, and especially the remains and scales 

 (Fig. 5, O, R, T) of the older larva; usually 

 contain this bacillus in very large numbers. In 

 making diagnoses such remains are looked for. 



t White. Circular 157, U. S. Dept. Agr.. 

 Bur. Ent, 1912. 



ment of larvae strongly suggests the 

 presence of the disease. A yellowish 

 wliite mass seen through the narrow 

 transparent area (Fig. 5, K) along the 

 median dorsal portion of the body 

 of the larva furnishes positive evi- 

 dence of European foulbrood (Fig. 5, 

 L). This mass is within the stomach 

 and is made up chiefly of a bacterial 

 growth composed largely of Bacillus 

 p7uton. 



A very satisfactory test and one 

 which may be applied even as early 

 as two days after infection takes 

 place, consists in removing the con- 

 tents from the stomach of a suspect- 

 ed larva. The larva is removed from 

 the brood-comb and is torn across 

 near the head end, leaving only the 

 contents of the stomach, which tears 

 less easily. By separating the two 

 portions of the larva the stomach 

 contents will be pulled out of the pos- 

 terior portion and be attached to the 

 anterior one (Fig. 9). The stomach 

 mass is broken into fragments by the 

 slight force necessary to remove it. 

 Conclusions 



European foulbrood is the disease 

 of bees that causes the death of the 

 brood during its uncapped stage. 



It occurs in many parts of the 

 United States and at least in Canada, 

 Denmark, England, Germany and 

 Switzerland. 



It is frequently referred to by the 

 general terms of "foulbrood." In this 

 country it was called "black brood" 

 for a while. That "stinking foul- 

 brood" and "sour brood" are also 

 names for this disease is the opinion 

 of the writer. 



The occurrence of the disease can- 

 not be attributed altogether to the 

 climate or food of the locality. The 

 season of the year and the quantity 

 of food are, however, factors which 

 determine to a certain extent the 

 course of the disease in the colony. 



The disease is infectious and is 

 caused by a germ named Bacillus plu- 

 ton. 



The worker, drone and queen lar- 

 va: are all susceptible to infection, 

 but the adult bees are not. 



The germs reach the stomach of the 

 larva: with the food. In the stomach 

 they multiply rapidly and during the 

 third day of the infection symptoms 

 of the disease appear. Death takes 

 place frequently by the end of the 

 third day. 



The sick and dead larvae naturally 

 contain the germs of the disease. 

 There is a strong tendency on the 

 part of adult bees to remove these 

 larvae. This is done in a piecemeal 

 fashion and the spread of the disease 



Fig. 8. Glass tube for inoculating larva; by the direct method 



