18 BULLETIN" 847, U. S. DEPARTMENT OF AGRICULTURE. 



of pairing seemingly depending about as much upon the volition of 

 one sex as the other. Xewly emerged males occupying cages in com- 

 pany with females have been observed to wait several days before 

 paying any attention to the females. In other cases they have begun 

 courtship on the day following that of their emergence. The females 

 usually repel the males for several days, but will sometimes receive 

 them within an hour after quitting the pupal quarters. Evidently 

 some individuals of both sexes remain in the wood until they are 

 sexually mature, while others issue before the sex instinct has 

 developed. 



The act of copulation usually lasts several hours and is repeated 

 at frequent intervals so long as both sexes live and are active. 

 Pairing was several times noted after the participants had been on 

 the wing from 30 to 40 days. 



Females confined by themselves were observed to engage in a 

 performance evidently to attract males. They would occupy the 

 upper surface of an exposed leaf and thrust out the ovipositor to its 

 utmost length and then wave it about while it was being gradually 

 drawn in. A few minutes later the ovipositor would be again ex- 

 tended and then drawn in and so the act would continue for an hour 

 or more. Apparently a scent or influence of some kind was being 

 discharged as a sex attraction, but when females so engaged occupied 

 outdoor cages no wild males of the locality were observed to come 

 to the cages. 



DAY AND NIGHT ACTIVITIES OF THE BEETLES. 



Early writers on this insect described the beetles as being active 

 nocturnally and secreting themselves by day. The beetles were sup- 

 posed to issue from their pupal cells and deposit their eggs exclu- 

 sively by night. The reverse of this habit, however, has been found 

 more nearly true. All the beetles issue from their exit holes by day, 

 usually during the forenoon, although a few continue to come forth 

 during the afternoon hours. Xo evidence was obtained that ovi- 

 position ever takes place in the darkness, although male beetles are 

 occasionally on the wing at night. There is a period of activity in 

 the evening just before twilight when both sexes are especially in- 

 clined to flight, but as darkness comes on most of the beetles settle 

 among the branches and remain quiet until the light of the morning. 



Observations made at night with electric flashlights indicated 

 that the normal habit is to rest in one place through the night, but 

 that occasionally the beetles move about in the darkness. 



DO THE BORERS DIFFERENTIATE BETWEEN VARIETIES OF APPLE? 



Orchardists often observe what appears to be a preference on the 

 part of the roundheaded apple-tree borer for certain varieties of 



