4 BULLETIN 424, U. S. DEPARTMENT OF AGRICULTURE. 



filled with earth by means of the abdomen, which is carried outward 

 from the tree and drawn back against it with the tip scraping the 

 loose soil. All evidence of injury to the tree is often obliterated by 

 the first succeeding shower. In the instances under observation ovi- 

 position required about one hour. 



After the egg has been covered the female crawls aimlessly about 

 the tree trunk. Her wanderings usuallj'^ end among the branches, 

 where copulation may occur, some of the tender leaves may be eaten, 

 or the female ma}^ take wing from the tip of a branch. 



The place of oviposition was discovered in July, 1913, when the 

 wind blew down cottonwood and willow cuttings in the Forest 

 Service nursery at Garden City, Kans. The forest supervisor, Mr, 

 B. E. H. D'Allemand, brought in damaged cuttings to learn the 

 cause of the injury at the surface of the ground. Field observations 

 revealed eggs in the Avounds on the sides of the cuttings, and these 

 eggs were identified as those of the cottonwood borer. Later they 

 were discovered in trees of all ages, and adults were observed in the 

 act of oviposition. The cuttings and younger trees were preferred 

 for egg laying. 



In 1913 the injury to cuttings was reported on July 29. At that 

 time the edges of many of the wounds had healed and many of the 

 eggs had hatched and the young had worked well into the tree. 

 About two weeks are required for hatching ; the eggs, therefore, must 

 have been deposited about July 10. On July 9, 1914, eggs were 

 found that had been deposited after July 4, as the work was fresh 

 and the last preceding rain occurred on the latter date. Oviposition 

 probably extends into September, as adults were numerous on August 

 22, 1914, and one was found on August 28, 1913. Mr. C. H. Popenoe 

 collected both sexes at Dodge City, Kans., September 23, 1913. They 

 were abundant, and several were found in copula. 



One female after depositing 2 eggs was found on dissection to 

 contain 13 others of different sizes, a total of 15; another female 

 deposited 1 egg and contained 15, a total of 16; a third deposited 1 

 egg and contained 16, a total of 17; and a fourth contained 23 after 

 depositing 1, a total of 24. During July of 1914 the average period 

 of incubation for 14 eggs was 13 days. 



DEVELOPMENT OF LARVA. 



On hatching, the young larva works out of the egg cavity and 

 begins to bore in the tender bark just outside of the wood. The 

 tunnel which it forms is usually filled behind it with excrement and 

 fine pieces of wood. As cold weather approaches it passes into the 

 wood, remaining either above or below the ground level. During 



