DIAGNOSING BEE DISEASES IN THE APIARY 



9 



Death occurs quite uniformly after the larvae have been capped 

 over, have spun their cocoons, and are fully extended on the floor 

 of the cells, as shown by the healthy larvae in figures 3, G, and 

 4, A. Occasionally death occurs after the pupa has formed but 

 before the body (except the eyes) is pigmented. (See healthy 

 pupae in figs. 5, A, and 6, A.) In advanced cases a few larvae may 

 die while coiled on the bottom of the cells (fig. 4, B), but only 

 rarely does death occur when larvae are irregularly twisted on the 

 side walls. Larvae killed by American f oulbrood that are coiled or 

 irregularly twisted often show symptoms similar to those of 

 European f oulbrood, and a laboratory examination may be necessary 

 to determine whether the latter disease also is present. 



COLOR AND CONSISTENCY OF THE DEAD BROOD 



Soon after death the glistening white color of healthy larvae and 

 pupae changes to dull white. About 2 weeks after death the color is 

 very light brown, and the well-rounded appearance is lost. The 

 dead brood gradually sink 

 in the cells during decay 

 and become darker (figs. 3 

 to 6), changing from a 

 light coffee color to dark 

 chocolate brown by the end 

 of the fourth week. Scales 

 are very dark brown or 

 nearly black. The decay 

 and drying of dead brood 

 ordinarily require a month 

 or more. Scales are diffi- 

 cult to distinguish in old 

 brood comb, since they are 

 about the same color as the 

 comb (fig. 2, D) ; but in 

 new comb they are readily 

 distinguished (fig. 2, C). 



During the early stages 

 of decay the body wall is 

 easily ruptured, and the 

 tissues are soft and watery. 

 Occasionally the body di- 

 visions of the dead larva 

 are more clearly marked 

 than are those in healthy 

 ones the consistency of dead brood becomes characteristically glue- 

 like about 3 weeks after death. When a toothpick or snatch is 

 thrust into a decayed larva and withdrawn, the decaying mass ad- 

 heres and can be drawn out an inch or more in a glulike thread 

 (fig. 7). Decayed larvae finally become dry and brittle. 



APPEARANCE OF THE DEAD BROOD 



The appearance and position in the cells of brood killed by Ameri- 

 can foulbrood are remarkably uniform. The dead larvae lie ex- 

 tended along the lower side wall with their posterior ends curved 



51309°— 36 2 



Figure 



American foulbrood ; ropy remains of a 

 decayed larva. 



