36° BULLETIN 1426, U. S. DEPARTMENT OF AGRICULTURE 
withered seed, but plants killed later in the summer may have set 
good seed. This injury late in summer and in the fall is due to the 
feeding of the rapidly maturing larve and the young adults (fig. 13). 
Injury is greatly enhanced by drought, and the extent and severity 
of the injury often seem directly related to the fertility, 01 at least 
the physical state, of the soil. 
Fic. 13.—Red clover roots, showing root borers and injury caused by 
em 
All the plants on four separate areas taken at random in a field at 
each of several places in Washington County, Oreg., the four areas in 
each field amounting in all to one ten-thousandth of an acre, were dug 
up, taken to the laboratory, and carefully examined to determine the 
extent of the damage done to them by clover root borers. The results 
are presented in Table 6. The record indicates considerable diversity 
in thickness of stand and brings out the more severe injury to clover 
on the poorer soil of the first field noted. Where clover fields are 
left for a second crop, the table indicates that the stand is, under the 
most favorable conditions, reduced approximately 50 per cent by the 
second season. When there is a good stand originally, a fair crop of 
hay may be obtained in the second season, and in a favorable season 
some seed may be harvested. 
