4 BULLETIN 886, U. S. DEPAKTMENT OE AGEICULTUEE. 



of an irregular, tortuous burrow, works its way to the heart of the 



branch. In the heart it burrows up and down for a distance of from 



4 to 6 inches (PL IV, A), finally making at the upper end of the 



burrow a curved extension outward to the inner bark (PL I, E, F). 



Through this the beetle escapes later by gnawing a circular exit in 



the bark (PL V, A, C). Badly infested trees take on a sickly, scrag- 



gly appearance, individual branches, and occasionally small trees, 



dying from the injury. 



LIFE HISTORY. 



The beetles issue from the wood by day in spring and early sum- 

 mer. In West Virginia they have been observed to appear from 

 May 14 to 31. At East Lansing, Mich., the beetles had apparently 

 all issued on June 26, 1916, but the year following (1917) in the same 

 locality all maturing individuals were still in the pupa stage on 

 June 15. 



As would be expected, the beetles appear earlier in the South 

 than in the North. There is probably a variation in the time of 

 emergence of several weeks between the southern and northern 

 limits of the species' range. 



After emergence the beetles seek the foliage of the trees and feed, 

 at times rather freely, on the bark of twigs and leaf petioles, and, 

 occasionally, on the leaves (PL V, D). .Copulation did not take 

 place with any of the beetles observed until about two weeks after 

 emergence. About a week after the first copulation, or three weeks 

 after emergence, oviposition began. Eggs may be laid by an indi- 

 vidual female over a period of at least 60 days. The eggs are placed 

 between the bark and wood (PL II, E), and hatch in about three 

 weeks. In some cases the larval period is two years, in others 

 three years, and, occasionally, it covers four years. The full-grown 

 larvae change in the spring to pupae, which occupy an open space 

 at the upper end of an elongate burrow, Visually in the heart of a 

 small trunk or branch (PL I, E, F; PL IV, B). The pupa stage 

 lasts from four to six weeks. After transforming to adults the in- 

 sects remain within the pupal cell for from one to two weeks and then 

 gnaw their way out through the bark. 



THE EGG. 



The egg is elongate, plastic, creamy-white when first laid, but chang- 

 ing to light brown within a few hours. (PL 1, A; PL II, E.) Several 

 specimens removed from their position beneath the bark averaged 

 4 mm. in length by 2 mm. in width. They were flattened, bluntly 

 rounded at the ends, the surface finely granular and marked by im- 

 pressions of the wood fiber which pressed them closely on both sides. 

 A free egg found in an oviposition scar was fusiform, slightly curved, 

 both ends tapering to rounded points, 3.7 mm. in length by 1 mm. 



