58 



DECIDUOUS FEUIT INSECTS AND INSECTICIDES. 



Table LIX. — Length of incubation of second-brood eggs laid in rearing cages, Douglas, 

 Mich., 1911; summary of Tables L VII and L VIII. 



Effect of temperature upon the time of incubation. — The general effect 

 of the temperature upon the time of incubation of the codling moth 

 eggs has already been considered on page 44 and the results for the 

 second brood of eggs have there been given in the diagram (fig. 15) 

 together with those for the first brood. In Table LVII the average 

 daily temperature is given for the 110 separate observations. These 

 temperature records have further been summarized to averages for 

 the respective days of incubation as given in Table LX. The range 

 in variation of average degrees of temperature for the different days 

 is shown in the same table in the columns of maximum and minimum. 



Table LX. — Average mean temperature during incubation of second-brood eggs, Douglas, 

 Mich., 1911; summary of Table L VII 



SECOND BROOD OF LARV.E. 



Time of hatching. — In the field the hatching period extended from 

 July 18 to October 3. The great majority of larvae hatched during the 

 latter part of July and throughout August; during September only a 

 few appeared. The period of hatching of larva? of the second brood, 

 extending over two months and a half, is very exceptional in compari- 

 son with the records for a normal season. During 1910 the period of 

 hatching of eggs of the second brood was less than one month and a 

 half. 



