﻿EFFECTS ON HONEYBEES OP SPRAYING FEUIT TREES 19 



Since none of the samples of dead bees collected before May 29 in this 

 apiary contained when analyzed more than a trace of arsenic (the 

 amount usually found in control samples) it is reasonable to suppose 

 that they had not visited the trees sprayed almost in full bloom 1 

 mile from their apiary. Before the weighed bees had visited the 

 sprayed trees they lost 18.12 ounces as a daily average, or 4.53 per 

 cent of their initial weight; after having visited the sprayed trees 

 they lost an average of 17.8 ounces per day, or 4.45 per cent of 

 the same initial weight. The theoretical daily mortality is 2.38 

 per cent. 



EESXJLTS OF CHEMICAL ANALYSES 



Samples of dead bees and pollen were collected and analyzed as 

 usual. Of 19 samples of dead bees analyzed, 10 yielded traces of 

 arsenic, although not enough to have Idlled the bees (see p. 24 to 26). 

 Of 9 samples of pollen analyzed, 2 contained no arsenic,. 2 a trace of 

 arsenic, and 5 arsenic in larger amounts although not enough to 

 have killed the bees. 



EXPERIMENTS AT DEUMMOND, MD., 1917 



The experiments just described were repeated on a small scale in 

 1917 at Drummoncl, Md., where the bee culture laboratory of this 

 bureau was then located. Observations extended from April 27 to 

 June 9. On April 30 the 11 apple trees there available were in full 

 bloom and the bees worked abundantly in them. On May 7, when 

 about 90 per cent of the petals had fallen and several bees were 

 still visiting the blossoms, these trees vs^ere sprayed. From this date 

 till May 14, when practically all the petals had fallen, very few bees 

 were seen visiting the sprayed blossoms, and during much of this 

 interval the weather was unfavorable for flying. On May 9 and 10 

 bees were observed collecting brown pollen from sprayed apple blos- 

 soms from which the petals had fallen. On May 26 they began 

 storing nectar; from June 2 to 9 there was a heavy honey flow, al- 

 though not from apple blossoms. 



On April 27 the total weight of the bees in the 6 hives weighed at 

 Drummond was 519 ounces. The daily losses (or gains) in ounces 

 from April 27 to May 12 inclusive, and on May 19, May 26, June 2, 

 and June 9, beginning with April 28 as the first day and ending with 

 June 9 as the 43d day (Table 5) were 34.75, 16, 9, 21.75, 0.75 (gain), 

 11.75, 3.5, 18.75, 19.75, 30.5 (gain), 40.5, 0.25, 5.75, 12.75, 18.5, 35, 

 27.5, 35.5, and 33 ounces. Before the weighed bees had visited the 

 sprayed trees they were losing daily 14.94 ounces, on an average, or 

 2.88 per cent of tlieir initial weight; after having visited the sprayed 

 trees, they lost dur-ing the first 6 days 7.88 ounces as a daily average, 

 which was 1.52 per cent of their initial weight, or they lost 1.01 per 

 cent as a daily average for the full i)oriod of 34 days after the trees 

 had been sprayed. The tlicoi-eiiciil daily mortality, based on six 

 weeks as the normal life of bees, is 2.38 per cent. 



Samples of pollen and bees were collected and analyzed as before, 

 but this tinrje the dead-bee traps wer-e not used. Twenty samples of 

 pollen were analyzed, none of which was found to contain arsenic; 

 10 of these were taken from the hives before and 10 after the trees 



