The Occurrence of Diseases of Adult Bees. 13 



the present discussion to take up the question of the losses incident 

 to the poisoning of bees by ill-advised applications of poisonous 

 materials in sprays used for the control of insect pests. There is 

 reason to think that in some instances serious results have come from 

 this use of arsenic. Aside from Isle of Wight disease and Nosema- 

 disease, this is the only other cause of death of adult bees which at 

 present can be determined by laboratory methods. 



NEGATIVE RESULTS. 



The most regrettable fact about the data so far obtained on the 

 diseases of adult bees is that so many of the samples have given 

 negative results. This is due partly to the fact that certain diseases 

 of adult bees exist for which the causes have not been determined. 

 The serious nature of the diseases of the brood of bees has made it 

 necessary that more attention be given to these, and while the causes 

 of the three diseases of the brood have been learned, little good work 

 has as yet been done on the diseases of adult bees. 



Attention should be called to the fact that many samples have been 

 received which could not be diagnosed by laboratory methods. The 

 greatest abnormal death of colonies of bees is doubtless due to poor 

 wintering or to losses indirectly to be attributed to this cause. The 

 condition known to beekeepers as dysentery is caused by an accumu- 

 lation of feces in the alimentary tract, due to a poor quality of food 

 and to a rapid accumulation due to excessive heat generation made 

 necessary by improper care in winter. These conditions have been 

 fully discussed in the publications of the United States Department 

 of Agriculture on wintering. In some instances it is possible to 

 surmise that the samples of dead bees have been taken from colonies 

 that have died because the beekeeper did not take proper care of his 

 bees in winter, but proof from laboratory diagnosis would be difficult 

 or impossible. When bees are received in early spring which show 

 a large volume of feces, this diagnosis is rather definite. 



A large number of cases possibly arise from the death of colonies 

 observed after brood-rearing has begun in the spring, and this the 

 beekeeper usually calls spring dwindling rather than winter loss. 

 It has been shown that the death of bees after brood-rearing is 

 under way in the spring is also a result of poor wintering, and should 

 properly be so diagnosed. There is no other known cause of the 

 condition known as spring dwindling. While laboratory proof of 

 such a condition is difficult, the well-known deficiency in winter 

 protection, so prevalent throughout the United States, suggests 

 this as a major cause of the death of bees submitted for examina- 

 tion. This has been recognized elsewhere than in the United States, 

 for in the work on the Isle of Wight disease in England it was found 



