292 J ojirnal of Agricultural Research voi. in. N0.4 



THE PUPA 



The pupal stage of the life history has been studied for the most part 

 in the laboratory. During the winter the larvae were collected in their 

 pupal cells and placed in wash bottles, which were then covered with cheese- 

 cloth. The larvae were found to contract and straighten out in such a 

 way as to face the end of the cell which is next to the bark. When con- 

 tracted ready for casting the lar\-al skin, the laws measured from 6 to 

 10 mm., instead of 18 to 24 mm., and were greatly swollen, with constric- 

 tions marking the posterior limits of the head, prothorax, and the loca- 

 tion of the appendages. Two or three days before the larval skin was 

 cast the posterior segments were collapsed and empty. When the pupa 

 was ready, it began a series of wavelike dorsoventral bendings, which 

 caused the skin to break on the dorsal side of the head and prothorax a 

 little to one side of the middle. As these movements continued the skin 

 was slipped gradually backward, collapsing as it left the posterior end 

 of the body, until it was entirely off, when the pupa came to rest (PI. 

 XXXVIII, fig. 7). The mouth parts passed to the ventral side and 

 seemed to act as a lever against the side of the cell in pushing the skin 

 backward. 



The pupal stage lasted about 10 days, during the latter part of which 

 pigmentation began with the eyes, then the mouth parts, head, and 

 thorax. The pupal skin was shed in much the same way as the larval 

 skin, and the adult folded the wings, remaining inactive until the elytra 

 were entirely pigmented. At first the movements of the adults were 

 slow and uncorrelated as contrasted with the great acti\nty later on. 

 The beetle burrowed through the bark as soon as it acquired its full 

 activity and escaped through a characteristic opening (PL XXXIX, 

 fig. 2). The openings are always found on the ridges of bark and resemble 

 the shape of the hole made by the larva when it first entered the bark. 



Larvse which had not yet pupated were collected as late as June 17, 



when adults were found making their way out from the pupal cells. 



From this it seems that the insect in this state normally pupates during 



the latter part of May and emerges from the cell about the middle of 



Tune. 



PARASITIC ENEMIES 



Two parasites were incidentally noticed. One, which was reared from 



the larvse, was identified by Mr. S. A. Rohwer as a species of the genus 



Atanycolus, while another, unfortunately mutilated, which was reared 



from an egg, was placed by Mr. J. C. Crawford in the family Tricho- 



grammidae. 



CONTROL OF THE OAK BORER 



The method of control heretofore recommended has been the cutting 

 and burning of infested trees before the emergence of the adults in the 

 spring. This is an effective method and needs emphasizing, for people 

 are tempted to leave all the trees which show any .signs of life, with the 



