THE FLIGHT ACTIVITIES OF THE HONEYBEE 



19 



3.15 to 3.45 A few drops are falling. 



3.45 to 4.00 Sprinkling. 



4.00 to 4.30 Steady shower falling. 



4.30 to 4.45 Sun shining brightly, though shower continues. 



5.00 Rain has stopped, bright sunshine. 



5.15 Again clouding over. 



5.45 A few drops falling. 



6.00 The sun is shining through the clouds for brief intervals. 



Although this day occurred between others of good honey flow, 

 the hive showed a loss in weight. An apparent gain in early after- 

 noon was due to water on the hive. Each period of rain caused a 

 decrease in flight, the heavy rain about noon causing the greatest 

 decrease. In each case the bees resumed flight promptly with the 

 slightest improvement of weather conditions. 



Fig. 7. — Flight, temperature, and hive-weight data for May 18, 1922, showing 

 the effect on flight of an overcast day with occasional showers 



THE EFFECT OF WIND 



Unfortunately for a thorough study of the effect of wind, there 

 were few days during the period of these observations when the 

 wind was strong enough to affect the flight appreciably. The in- 

 formation is drawn from the records of only five days, and such 

 statements as can be made on this subject are therefore made with 

 some reservation. 



April 11 was a windy day, with no substantial honey flow. The 

 successive numbers of exits increased with the rise in temperature 

 until 8.30 a. m. During this period the velocity of the wind was 

 only 4 to 5 miles per hour. Between 8.30 and 9 a. m. the wind 

 velocity reached 10 miles per hour and the flight dropped and con- 

 tinued low, while the velocity of the wind increased to 11 and 15 

 miles per hour. At 2 p. m. the velocity fell to 6 miles per hour 

 and later to 4 miles, with the flight responding by an increase, which 

 no other observed factors would explain. 



This record might suggest that a velocity of 10 miles per hour is 

 the minimum velocity appreciably affecting flight. However, this 

 can not be the case, for on April 10 a play flight took place, when 



