OCTOBER 1, 1916 



913 



GENERAL CORRESPONDENCE 



SACBROOD MORE DISASTROUS TO COLONIES THAN HAS BEEN GEN- 



ERALLY SUPPOSED 



RY BrUTON X. GATES 

 Associate Professor of Beekeeping, Massachvsetts AgricvUural College, Amherst. 



Beekeepers are inclined to disregard tiie or larvae. There were, besides, a considera- 



presenee of sacbrood in their colonies. It ble number of empty cells, or cells with 



is often imperfectly understood that this _ eggs among irregularly arranged healthy 



disease may be disastrous in an apiary. If brood in all stages. Thus about 27+ per 



it occurs in even a slight form, it is deplet- cent of the brood was infected witli sac- 



ing. Accurate figures of the damage which brood. 



it can cause are difficult to obtain. Its viru- Case 2, count made by the writer June 



lence apparently differs in different seasons, 24, 1915, Newburyport, Mass. The comb 



apiaries, and colonies. The strain of bees used in Case 1 was reversed, and a block of 



apparently has much to do with the evident cells 13 by 45 was marked off, containing 



symptoms of the disease. Not infrequently 585 cells. ' The block of cells was selected 



a beekeeper says that his bees are not sub- at random. Of this group of cells 50+ 



ject to sacbrood, or that if sacbrood occurs cells were sacbrood or 8+ per cent, 



it is soon cleaned out. Occasionally col- Case 3, count made by the writer June 



onies are found in wliich disease is not 29, 1915, Rowley, Mass. A typical, bad 



readily suppressed, either thru the efforts case of infection was found. From the 



of the beekeeper or by the bees themselves. center of the brood-nest was removed a 



Sometimes beekeepers treat or shake to rid comb upon which was marked off a gi'oup 



the colony of sacbrood, the same as they of 800 cells, 40 cells in a row and 20 rows, 



would a colony diseased with European foul Counts were made as follows : 



brood or American foul brood. It is not, Total number of cells 800 



however, usually necessary to resort to these Number of empty cells or cells with 



drastic measures. The introduction of a honey , 98 



more vigorous strain of bees — that is, the ■ 



introduction of a queen of virule type, will Balance -^ ^^^^^ "^ healthy larvae. .330 



usually do away with the disorder. „ j «ells of sacbrood 372 /02 



T\ ■ J I ^ 1 ni - 1 Per cent of infection, 53. 



JJuring the season or 191o several severe ' 



cases of ^sacbrood came under the observa- The 20 rows of 40 cells each extended 



tion of the writer, in which the infection fi'om the top to the bottom of the frame, 



was exceptionally pronounced. In fact, a thus affording a complete section of the 



careless glance at the combs suggested the brood-nest. In order to furnish a more 



presence of American foul brood. The api- complete comparison the data for each row 



aries in which this infection was found of cells are tabulated below : 



have had sacbrood for some years, varying Row Cells of sacbrood 



from time to time in intensity. General ^ ^'^ Top of frame, 



observations around Massachusetts indicate " ^^ 



that such conditions are not infrequent. . 24 



With proper measures, however, the disease g 30 



can be obliterated. 6 21 



It is not the purjiose of this discussion to 7 24 



consider the nature, cause, or treatment of 8 21 



the disorder, but more especially to give a ^ la 



gTaphic account of extreme cases of sac- | ^^ 



brood. For concreteness, three cases are ,p 29 



presented. j3 20 



Case 1, count made by the writer June 14 20 



24, 1915, Newburyport, Mass. A colony 15 15 



which was obviously badly infected was 16 16 



selected. At random, a block of brood on 17 19 



one of the combs was marked off, 18 cells 1^ ^ 



by 25 cells, making in all a group of 450 „;; o -d 4.^ f f,„,«o 



•'.. -^ ' ^ 5 ^, ,,^ ,/ 20 8 Bottom of frame 



cells. By count or these cells, there were 



125 which contained either sacbrood scales 372 



