ECONOMIC ZOOLOGY — ENTOMOLOGY. 255 



liminarj' report presents the results of the first season's work on the behavior 

 of bees during the winter. The authors have eliminated a source of error, 

 through the use of electrical thermometers in place of mercury thermometers, 

 thus being enabled to take the readings of the temperature of various parts of 

 the hive without opening the hive, or going near to disturb the bees. In all 

 161,617 temperature readings were made during the winter of 1912-13. 



The authors find that " when the temperature of a colony of undisturbed 

 broodless bees is above 57° F. and below about 69° the bees are quiet and their 

 temperature drifts with the outer temperature ; at lower temperatures they 

 form a compact cluster, and the temperature within it is raised by. heat gener- 

 ated by the bees." While the lower critical point, 57°, appears rather well 

 established, it is stated that the observations up to the present do not justify 

 too definite a statement as to the upper limit of quiescence. These conditions do 

 not apply when the colony has brood, since the rearing of brood in winter causes 

 a marked increase in heat production and constitutes a condition which may 

 become one of the most disastrous that can befall a confined colony. 



The studies indicate that dextrin can not be digested by bees. Thus honey- 

 dew honey causes a rapid accumulation of feces which usually results in the 

 condition known as dysentery, in bad cases of which the feces are voided in the 

 hive. " The accumulation of feces acts as an irritant, causing the bees to be- 

 come more active and consequently to maintain a higher temperature. We are 

 therefore justified in believing that the cause of poor wintering on honeydew 

 honey is due to excessive activity, resulting in the bees wearing themselves out 

 and ultimately in the death of the colony. . . . The accumulation of feces due 

 to confinement causes increased activity and this in turn is the cause of ex- 

 cessive heat production, resulting in a reduction in the vitality of the bees. . . . 

 While the activity of the cluster is greater at some times than at others, there 

 are not, as has been held, regular intervals of activity at which the colony 

 rouses itself to take food. At no time is a colony kept at a room temperature 

 of 45° or less in a condition which can be characterized as inactive. . . . Poor 

 food is evidently a more serious handicap than low temperature." 



The authors state that it is clear that the heat for the warming of the 

 cluster is produced by muscular activity. " It is at least evident from the rec- 

 ords obtained in this work that colonies of bees in winter, either in cellars or 

 out of doors, should be disturbed as little as possible. This appears to apply 

 especially to cold weather out of doors or in the cellar, especially after the 

 colony has been confined for some time." 



Destruction of germs of infectious bee diseases by heating, G. F. White 

 (U. S. Dept. Agr. Bui. 92 {1914), PP- 8). — In this bulletin the author summarizes 

 the results of 55 heating experiments carried on during the last two years. 



When maintained for 10 minutes the minimum temperatui-es that can be used 

 for destroying the germs of the four bee diseases now known to be infectious 

 apparently are approximately 63° C. (145.4° F.) for European foul brood, 

 98° for American foul brood, 58° for sacbrood. and 57° for Nosema disease. 



" It is probable that future experiments may cause slight changes to be made 

 In these conclusions. Nothing more than a comparatively slight variation is to 

 be expected, however. In practice the beekeeper, in destroying these germs by 

 heating, will naturally use a quantity of heat somewhat in excess of the 

 minimum amount that is absolutely necessary." 



Dipterous enemies of the Melipona bees, R. Ramirez (Bol. Dir. Gen. Agr. 

 [Mexico], Rev. Agr., 2 {1912), No. 6, pp. 533-535, pis. 2). — Phora incrassata and 

 P. aterrima are mentioned as enemies of the immature stages of Melipona bees. 

 55733°— No. 3—14 5 



