KOinSTDHEADED APPLE-TREE BORER. 



27 



500 yards distant. That such flights are unusual, however, is indi- 

 cated by all the evidence that could be gotten. 



FEMALES LESS PRECOCIOUS THAN MALES. 



The females are not only less active in flight and more sluggish 

 generally than the males but are regularly two or three days behind 

 the males in issuing from their pupal quarters in the wood. This 

 constant tendency on the part of females to be slower than the males 

 in emergence is illustrated by figure 5. 



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Fig. 5. — Saperda Candida. Diagram illustrating the relative time of emergence of male 

 and female beetles. Based on 261 males and 206 females that issued under natural 

 conditions at French Creek, W. Va„ in 1914, 1915, 1917, and 1918. 



SEASONAL PHENOMENA OF THE HOST TREES AS AN INDEX TO 

 THE TIME OF DEVELOPMENTAL CHANGES OF THE INSECT. 



Since this borer occurs in North America from southern South 

 Carolina and Texas northward into Canada the calendar dates of its 

 metamorphic changes in different latitudes must vary considerably. 

 There must also be a considerable yearly variation in the dates of 

 these changes in any given locality, due to the early or late advent of 

 spring. 



In the rearing work with this species it was found that between 

 Demorest, Ga., and Winthrop, Me., there was a difference in time of 



