August, 1921 



GLEANINGS IN BEE CULTURE 



491 



(3) There is some evidence to indicate 

 that a lower minimum than 60° is even bet- 

 ter. 



(4) A higher minimum than 62° seems 

 decidedly adverse to nectar secretion. 



(5) A higher temperature, or a longer 

 period of a given temperature seems neces- 

 sary to bring across nectar freely on cloudy 

 days than when the sun shines; that is, bees 

 will not work as freel^y, and the nectaries do 

 not show as much fresh nectar in as short 

 a time when the weather is cloudy as when 

 the sun shines. In short, it seems to take 

 longer "to get things going" in cloudy 

 weather, even the the artificial temperature 

 is normal, or identical. 



(6) A rapid rise from minimum to maxi- 

 mum brings better secretion. Not only then 

 does the nectar come more copiously, but 

 also earlier in the morning. As the average 

 temperature in greenhouses, rises from about 

 61° at 6:00 a. m. to about 72° at 8:00 a. m., 

 and then is raised to about 80° by 9:00 or 

 10:00 a. m., it was easy to observe the time 

 and the hour, with corresponding effects on 

 the time of the bees getting out to work. 

 Seldom did they start before 7:30 a. m., 

 and usually not till 8:00 or 8:30 a. m. Bees 

 normally fly out for nectar at a temperature 

 of 65°. It was a matter of wonder to me 

 that, tho the temperature of about 61° of 

 the night preceding in the greenhouses was 

 only about four degrees below the flying 

 temperature of 65°, seldom did the bees fly 

 out before 8 o 'clock in the morning. Was 

 it the fact that only sugary crystals of 

 dried-down nectar were in the blossoms to 

 entice them, and that they came out only 

 when liquid exudation set in? It surely 

 seemed so. 



(7) On cloudy days, when bees work at 

 all normally, they seemed to spread their 

 gathering time over a longer portion of the 

 day. It may be that the temperature on 

 cloudy days did not so soon pass the opti- 

 mum for nectar secretion. 



(8) But little nectar exudes in nectaries 

 of cucumbers at temperatures below 70 °F. 



(9) The optimum for nectar secretion, 

 and hence for flying of bees, seems to lie 

 somewhere between 70° and 80°F. 



(10) After an optimum has been reached, 

 a sudden marked drop in temperature slows 

 down secretion. (Note the data on March 17, 

 Plant A, Kange 4.) 



(11) A temperature of 90° or more at 

 hive level means, of course, a much higher 

 temperature at the roof, and hence at that 

 temperature bees are overcome or incapaci- 

 tated for work, and fall to the ground or 

 cluster helplessly on rafters or plants unless 

 ventilators are opened; in that case, they fly 

 out and so escape the disastrous effects of 

 high temperatures. 



Comparison with Kenoyer's Observations. 

 A comparison of the data observed above, 

 and the conclusions recorded by Kenoyer, 

 in Bulletin 169, Iowa State College of Agri- 

 culture, 1917, "The Weather and Honey 



Production," and also his Bulletin of the 

 Iowa Experiment Station No. 37, "Environ- 

 mental Influence on Nectar Secretion," are 

 interesting, not to say convincing. 



His deductions, made on the data gath- 

 ered by Mr. Strong of Clarinda, Iowa, are 

 fifteen in number, the first few of which re- 

 fer to the Iowa seasons by months, to the 

 influence of rainy seasons, and to the direc- 

 tion of the winds. No. 8 in his summarized 

 conclusions reads, "Good honey months av- 

 erage slightly higher in temperature than 

 poor, this being especially true of the spring 

 and fall months." No. 9 reads, "Clear 

 days are favorable to production of honey. ' ' 

 No. 10 is, "Yield is best on days having a 

 maximum of 80 to 90°F." No. 11, "A wide 

 daily range of temperature is favorable for 

 good yield." No. 12, "A low barometer is 

 favorable for a good yield." No. 13, "The 

 fluctuations in yield for a producing period 

 seem to be closely correlated with the tem- 

 perature range and the barometric pressure, 

 acting jointly." 



His deduction No. 8 means that there are 

 for different flowers temperatures too low 

 for good nectar secretion. In the green- 

 houses we found no nectar in the cucumber 

 blossom below 60 °F., but only dried-down 

 crystals of sugary nature remaining on nec- 

 taries. Regarding No. 9, sunshine in green- 

 houses always seemed to accompany best 

 nectar secretion below 80 °F.; above that, 

 it accentuated the drying up of nectar. As 

 stated earlier, however, it is hard to separ- 

 ate the sunshine from some other factors 

 favoring nectar secretion. As regards No. 

 10, the yield from the clovers, basswood, 

 and smartweed is optimum at a range be- 

 tween 80 and 90 °F. Cucumbers seem to 

 yield best ten degrees lower, that is, between 

 70 and 80 °F. No. 11 is especially interest- 

 ing in a comparison with our greenhouse 

 conclusions. The evidence in the cucumber 

 nectar-secretion tests is decidedly in favor 

 of the conclusion that a lower minimum pro- 

 duces better secretion than even a minimum 

 of 60 °F. The plants are usually watered 

 about two o'clock in the afternoon; and it 

 was noted often that the bees seldom worked 

 on the blossoms during nor after a watering; 

 the air in a greenhouse, after a thoro wet- 

 ting down, such as is given daily, is humid 

 and sultry, much like a midsummer day 

 when the sun comes out after a heavy show- 

 er. Even in those houses where the water- 

 ing is done under the vines about the roots, 

 and not by overhead spraying, the effect 

 of the great humidity ensuing always 

 seemed to check or stop the activity of the 

 bees and the deposits of nectar, in some de- 

 gree at least. Probably accurate barometric 

 readings of the houses under observation 

 would be more conclusive. As to Ken- 

 oyer 's deduction No. 13, about the effect 

 a temperature range and barometric range 

 acting jointly have on nectar production, 

 further tests in houses under glass must be 

 made, and will l)e made this year, to deter- 



