﻿EFFECTS ON HONEYBEES OF SPEAYING FRUIT TREES 29 



isolated; (3) they are slightly affected when a small orchard is 

 sprayed in full bloom, a conclusion supported by observations and by 

 the analyses of the samples of bees collected; and (4) of the three 

 mixtures named, the arsenate-lime-sulphur mixture was found the 

 most satisfactory for experimental purposes. 



In the more extendecl experiments conducted at Winthrop, Me., 

 1914, a large isolated commercial orchard, consisting of 700 apple 

 trees and almost ideally located, was selected, and 10 colonies of bees 

 were installed in it on May 29 and 30. On May 25 and 26 all of these 

 trees, nearly in full bloom, were sprayed with a mixture of paste 

 lead arsenate and lime-sulphur; on May 28 and 29, 310 of them, now 

 in full bloom, were again sprayed with the same mixture; and on 

 June 3, 5, and 6 the entire orchard was again sprayed. 



The unusual mortality of the bees at Winthrop was first noticeable 

 the second day after they had had access to the sprayed flowers, and 

 on the third day after they had been poisoned the damage was un- 

 mistakable. This heavy mortality continued as long as the sprayed 

 flowers lasted, and in some of the colonies until all the bees had died. 

 The symptoms of arsenic poisoning were very pronounced. In the 

 early stage the adult bees became sluggish and soon neglected 

 their duties, so that the brood apparently died of starvation; later 

 their abdomens became greatly swollen, being filled with a yellow- 

 ish waterj^ liquid; still later the legs and wings became paralyzed; 

 and finally the bees died in a state of coma. Not one of the 10 

 colonies used was killed outright, but in a comparatively short time 

 5 of them were entirely depopulated, while the other 5 were rendered 

 more or less weak. It was thus ascertained that spraying fruit trees 

 in full bloom under certain conditions is very injurious to bees. 



The results obtained from the chemical analyses of the samples 

 collected at Winchester and Winthrop agree with the field observa- 

 tions. Arsenic was found on all parts of the sprayed flowers, par- 

 ticularly on the pollen, and in most of the samples of the adult bees 

 analyzed, but none was found in the samples of dead pupse and 

 larva?. Of 12 samples of partially ripened honey analyzed only 1 

 contained arsenic, and that merely a trace. Dr. E. E. Tyzzer, of the 

 Harvard Medical School, reports by correspondence that during the 

 spring of 1920 and that of 1921 he experimented along isimilar lines. 

 He says : 



I have had analyzed two samples of unripe honey, gathered during the spray- 

 ing of fiiiit trees in full bloom, and found that both showed a very slight 

 trace of arsenic. A sample of " honeydew " saved from a previous year showed 

 0.0004.5 per cent of ai'senlc, and another of ripe honey of good quality showed 

 no trace of arsenic. 



It thus seems that the bees obtained most of the arsenic from the 

 pollen, altlioiigh most of the nectaries analyzed contained arsenic. 

 We should expect the honey to be poisoned, but so far only traces of 

 arsenic have been foimd in it (see Table 1 foi" details). 



The preceding results weie obtained by daily observations, the 

 u.se of .several dead-bee traps, and analyses of the samples collected. 

 One of these traps was installed in front of each hive selected for 

 thiiS purpose; it caught most of the bees that died in the hive, but 

 their number was only about 2.5 pei- cent of the total mortality, the 

 other 07.0 per cent dying in the field. When the mortality was heavy 



