88 Psyche [August 



The relation between fecundity and the proportion of sexes in 

 the various types of burrows is shown by the following tables of 

 data: 



Number of Egg-niches in the Egg-galleries, Based on a Study of 40 



Engravings. 



No. of 



Average no. of engravings 



egg-niches. studied. 



Uniramous engraving 23 6 



Biramous " . '. 41 . 04 23 



Triramous " 48 . 9 11 



Average number to engraving 40 . 5 40 



Egg-gallery of uniramous engraving . . 23 6 



" biramous " . . 20.5 46 



" triramous " ..16.3 33 



Average number, all types 19.05 85 



From the above it is evident that each female under monogamic 

 conditions produces more eggs than under conditions of bigamy or 

 polygamy; but just as with Polygraphus rufipennis Kirby and 

 Eccoptogaster piceoe Swaine (Blackman and Stage, loc. cit., pp. 45, 

 53) , the greatest individual reproductive efficiency exists when the 

 burrow is occupied by one male and two females. 



The larval burrows at the start are at nearly right angles to the 

 egg-gallery (Plate IV, fig. 2) and are entirely in the inner bark. 

 As they proceed farther, however, they groove the sapwood deeper 

 and deeper and show a tendency to become winding in their course. 

 These larval mines end in oval pupal chambers excavated nearly 

 entirely from the sapwood. The new generation of adults continue 

 feeding in the old host for weeks or sometimes even months before 

 reaching sexual maturity. If young adults, fully mature so far as 

 coloration and general appearance are concerned, are removed 

 from their larval host tree and confined with new pieces of pine 

 they will usually not breed until they have fed on the inner bark 

 for a week or more. 



On March 20, 1915, a number of young adults, removed from 

 their hibernating quarters, were confined with several suitable 

 pieces of white pine. Within two days all but a few, which had 

 died, had entered the cut ends of the material, all of them making 



