82 MASS. EXPERIMENT STATION BULLETIN 234 



Weather and Activity of Bees Remarks 



Fair, warm ; active A few buds showing pink tips 



Coo] wind ; slight activity 

 Cool wind; very slight activity 

 Cool wind, cloudy; very slight 



activity 

 Cool wind, cloudy; slight activity 

 Cool wind, cloudy; very slight 



activity 

 Cool wind, cloudy, some rain; 



very slight activity 

 Fair, cool; slight activity 



Fair, warm; very active Blossoms opening 



Cloudy, rain; very slight activity 

 Windy, warm ; active Combined spray 



Rain; slight activity 

 Warmer, cloudy; very slight Lead arsenate alone 



activity Bloom all out or nearly so 



Clear, warm ; active 

 Windy, warm ; active 



Pair, cooler; active Petals beginning to fall 



Fair, warm late in day; slight 



activity 



22 150 69° Fair, warm ; active Peach bloom over 



Apple blossoms introduced 

 Lead arsenate alone 



23 42 58° Cloudy, cool ; very slight activity 



24 142 60° Fair, warm ; active 



25 236 63° Fair, warm, windy, active 



26 107 61° Fair, warm ; active Combined spray 



27 174 55° Cloudy, cool ; some active 



28 202 58° Fair; active 



29 105 64° Fair, warm ; active 



30 94 63° Muggy; active 



31 78 57° Cloudy, rain, warm ; slight activity 



The bees sliowed the same reaction toward tlie combined spray as was 

 noted in 1925. They were noticeably repelled, particularly while the spray 

 remained as drops upon the blossoms. No such repellent action was noted 

 when lead arsenate was used alone. Figure 2 shows the mortality curve of 

 the bees in relation to the spray applications made. 



It will be noted that there was a sharp rise to a high peak of mortality 

 following the first lead arsenate spray. There was also a sharp rise, al- 

 though not so great, the second day following the second lead arsenate 

 spray. The slightly increased mortality two days after the second com- 

 bined spray may be due in part to the spray but appears to be more closely 

 correlated with the rise in temperature conditions. 



There were four high peaks of mortality reached during the experiment, 

 as follows: 



May 13. 237 dead. Av. temp. 68°F. No spray involved. 



May 18. 325 dead. Av. temp. 73'~F. Following lead arsenate. 



May 25. 2.36 dead. Av. temp. 63°F. Following lead arsenate. 



May 28. 202 dead. Av. temp. 58° F. Following combined spray. 



The peaks of the 13th and 25th were practically the same; occurred at 

 temperatures of only 5° difference and under conditions which would ap- 

 pear to give no significance to the lead arsenate spraj^ which had been ap- 

 plied three days previously. There is one differenee, however; the peak of 

 May 13 was at the culmination of a steadily rising temperature for two 

 or three days; the peak of the 25th occurred after the average temperature 

 had fallen for two days and had then risen but a degree or two. Both 

 peaks, however, followed the resumption of activity of the bees after a 

 period of but slight activity, lasting one to two days; so that, while the 



