THE POISONING OF BEES BY ORCHARD Sl'RAYS 79 



fined wliile tlie spray was applied. The same materials and dilutions were 

 a])plied as a spray just after the height of bloom had been reached. 



Scarcely any bees worked the bloom during the remainder of the day 

 after spraying, and very few the following day. During the next two days 

 some bees were observed working the bloom but not as freely as before 

 the trees were sprayed. Heavy rains and high wind followed, which pre- 

 vented activity of the bees, and when favorable weather returned there 

 was little bloom left to attract the bees to the trees. 



The colony was kept under observation for ten to twelve days after the 

 spray was applied, to note any marked increase in mortality. During this 

 period less than one hundred dead bees were collected. The greatest num- 

 ber found in any one day was fifteen. Some of the bees collected from the 

 sheet before the hive entrance showed characteristic symptoms of spray 

 poisoning. Frequent examination of the colony during the experiment and 

 at its close showed it to be healtiiy and in normal condition. 



In this experiment, as in tiie jireceding, there was evidence of a marked 

 repellent action of the spray on the bees for at least one or two days, and 

 at no time after tiie spray was api)lied did tiie bees visit the blossoms in 

 such numbers as before. Some few bees showed symptoms of spray poison- 

 ing, indicating tliey had worked the sprayed blossoms. The mortality was 

 so insignificant, however, as to make it evident that most of the bees availed 

 themselves of the abundant unsprayed bloom in nearby orchards. 



Experiments xcith trees enclosed in tentin(j. 



The colonies in the orchard experiments above had in each case failed to 

 show any serious effects from exposure to sprayed bloom. The combined 

 spray, while unattractive to the bees, had been found to be very toxic to 

 them, even when taken in small amounts. It was possible, therefore, that 

 many of the bees had died or become disabled before they could return to 

 the hive. Examination had shown but few bees dead or dying beneath 

 sprayed trees. In an orcliard in grass, however, it was almost impossible 

 to make an accurate collection. 



It has been observed by beekeepers that bees forage over a radius of at 

 least two miles from tiie hive in search of nectar and pollen. It was pos- 

 sible, therefore, that the bees in the experiment traveled to other orchards 

 near by and also tiiat otiier bees were visiting our sprayed trees. The Col- 

 lege Apiary and one or two private beekeepers were located within this 

 urea of possible danger. 



To determine with greater accuracy the mortality of the bees and also 

 prevent possible damage to neighboring colonies, the experiment was con- 

 ducted during 1925 using trees enclosed within tenting. 



Four twelve-year-old peach trees were covered with two thicknesses of 

 tobacco tenting, enclosing an area approximately forty feet square. Cloth 

 was spread on the ground within the tent to facilitate collection of dead 

 bees. A colony of bees was placed within this area and allowed several 

 days to become accustomed to their surroundings. 



When considerable bloom had opened, the trees were sprayed with the 

 combined mixture. Several days later, when the bloom was at its height, 

 another application was made in order to cover the newly-opened blossoms. 

 In one spray, lead ar.senate alone was used. When peach bloom had passed, 

 masses of apple blossoms were supplied the bees. 



