78 MASS. EXPERIMENT STATION BULLETIN 234 



Orchard Experiments. 



In Massachusetts, apples are the main orchard crop. Since bees do not 

 visit the orchards to any extent except when the trees are in bloom, the 

 two sprays involved are the pink and the calyx. The pink is scheduled to 

 be applied just before tlie blossoms open, and the calyx when about 90 per 

 cent of the blossom petals have fallen and before the calyx cups close. The 

 fruit grower sprays when most of the trees are in the proper condition. 

 The period allowed for these sprays, however, is limited. If unfavorable 

 weather is encountered, the pink may not be completed before some of the 

 blossom buds have opened. In a mixed planting, certain varieties come 

 into bloom later than others. There is also considerable variation in the 

 bud development in a single tree. This means, therefore, that for the 

 calyx spray especially, the grower must often spray when some blossoms 

 are open. The following experiments were conducted to determine what 

 effect these sprays ha\e upon bees. 



Effect of a late pink application. 



A normal ten-frame colony was placed in the center of an orchard several 

 days before the trees were to be sprayed. A sheet was spread in front of 

 the hive to facilitate observations on the behavior of the bees, if any should 

 show symptoms of poisoning. 



When the center bud of the blossom clusters had opened and the other 

 buds were .just separating, the bees were confined and the trees thoroughly 

 sprayed with the combination of lead arsenate, 1 Vo lbs. to 50 gallons; lime- 

 sulfur, 1:40; and nicotine sulfate, 1:1000. The bees were then released 

 and their reaction noted. 



Several hours after the spray was applied, a few bees were observed 

 visiting the blossoms. During the next two days, the bees showed slightly 

 greater willingness to work upon sprayed bloom, but never did so in large 

 numbers. The trees soon came into full bloom and tlie bees began working 

 the blossoms normally. 



During the five days following the spray, including one stormy day when 

 the bees were inactive, less than fifty dead bees were collected on the sheet 

 ill front of the hive. A few bees collected from sprayed blossoms and 

 l)laced in cages for observation, in a short time showed typical symptoms of 

 poisoning and died within twenty-four hours. So far, however, from becom- 

 ing disabled by exposure to sprayed bloom, the colony within a week was 

 found to be upon the point of swarming. 



The experiment demonstrated that bees wliich actually worked the 

 sprayed blossoms were poisoned. The trees opened into full bloom so 

 quickly after tlie time the spray was applied, however, that the bees had 

 ample opportunity to work bloom containing no poison, so that the loss to 

 the colony was negligible. 



Effect of an early caljx sprai/. 



A colony similar to that used in the previous experiment was placed in 

 a block of twenty-one apple trees in bloom, which the bees worked freely. 

 A sheet was spread in front of the hive, as before, and the bees were con- 



