﻿8 BULLETIlSr 1364, U, S. DEPARTMENT OF AGEICULTUEE 



A bee collecting pollen also usually alighted on the bunch of 

 anthers and stigmas. It removed the pollen from the anthers with 

 its mouth parts, and, in transferring the pollen to the pollen baskets 

 by means of the legs, much of the pollen adhered to the hairs on all 

 the legs. A few bees were seen completely covered with pollen dust. 

 When a bee returns to the hive with its load of nectar or pollen, it is 

 usually cleaned before it leaves the hive again, most of the pollen 

 dust adhering to the hairs being removed. The cleaners certainly eat 

 some of the pollen dust removed, for bees in an observation hive are 

 often seen to steal pollen from the pollen baskets before the bee 

 carrying the pollen has placed its burden in a cell. Bees collecting 

 the pollen probably swallow a small portion of the . grains while 

 biting them loose from the anthers. 



RESULTS OF CHEMICAL ANALYSES 



To ascertain whether chemical analyses would corroborate the 

 results obtained by observation, many samples were collected on 

 various dates, consisting of parts of sprayed flowers, fresh pollen 

 from legs of bees and from combs, honey, entire bees, foreign sub- 

 stances removed from bees, parts of bees, dead pupse, and dead larvae. 

 The results of analyses of these samples are briefly summarized in 

 Table 1, which, with the exception of the last column, is self-explana- 

 tory. In that column the weight of arsenic found is expressed as 

 parts per million in terms of metallic arsenic (As). For illustration, 

 let us consider a sample containing flowers without the anthers and 

 stigmas. The entire sample weighed 6.031 grams (about 0.21 ounce) 

 and the metallic arsenic found in it weighed 0.1 milligram (about 

 0.0000036 ounce ) . One tenth of a milligram is found by a simple com- 

 putation to be 16.6 millionths of 6.031 grams. The weight of arsenic 

 found in the sample is therefore 16.6 millionths, or parts per million, 

 of the weight of the sample itself. 



Of all the parts of the flowers analyzed the pollen bore the most 

 arsenic. Expressed as parts per million (using only whole num- 

 bers), pollen from the legs of bees bore llY (Table 1) ; fresh pollen 

 stored in the hives, 96 ; anthers and stigmas of sprayed flowers, 55 ; 

 and sprayed flowers, not including the anthers and stigmas, which 

 had been cut off, 32. 



Of the 12 samples of honey analyzed only 1 contained arsenic, and 

 that only a trace. Most of this honey was probably collected before 

 the bees had been installed in the sprayed orchard. Entirely un- 

 ripened honey was scarce, perhaps owing to the fact that the bees 

 ate the honey almost as rapidly as it was collected. In the pre- 

 liminary experiments 18 samples of more or less unripenecl honey 

 were collected, but when analyzed not 1 of them was found to 

 contain arsenic. 



Nectaries carefully dissected from flowers sprayed in full bloom 

 bore 0.0003 milligram each of arsenic, on an average (Table 1) ; 

 nectaries from other flowers, sprayed after the petals had fallen, 

 bore each 0.0007 milligram of arsenic. In computing these averages 

 and others in Table 1 only the samples containing arsenic (As) were 

 considered. 



