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 usually end among the branches, 
where copulation may occur, some of the tender leaves may be eaten. 
or the female may 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. R. 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 wounds on the sides of the cutting-, 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. 1911. eggs were 
found that had been deposited after July 1. 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. 1911. and one was found en August 28. 1913. Mr. C. H. Popenoe 
collected both sexes at Dodge City. Kans.. September 23. 1913. Thev 
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 21. During July of 1911 the average period 
of incubation for 11 eggs was 13 days. 
DEVELOPMENT OF LARVA. 
On hatching, the young larva works out of the egg cavity ami 
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 
