BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 43 
for such bark beetles. This is contrasted to earlier work that em- 
phasized the removal of all elms over 50 percent dead and excluded 
the pruning of branches. More attention was given this year to the 
destruction of wood piles and slash. Fifteen illustrations were 
prepared describing elm wood considered easy prey for bark beetles 
as well as wood not likely to be attacked by beetles. Using these 
illustrations, supervisors gave held crews special training in the 
recognition of wood involving the greatest hazards. An analysis of 
the results obtained showed that, with thorough elm sanitation as 
an objective, 95 percent of all beetle-infested material could be de- 
stroyed in 80 percent of the time required in the absence of this type 
of training. In areas where manpower was so limited that a thor- 
ough job could not be attempted, it was possible to remove 80 percent 
of all beetle-infested material and 10 percent of the material that 
might become infested in 30 percent of the time that would have been 
required to carry on the sanitation program of previous years. 
The selective removal of such material was found to be of further 
advantage during the spring and early summer of 1940, when most 
of the work area was rechecked to remove infested material before 
beetle emergence. This work was largely limited to removal of the 
five categories of beetle material considered the most dangerous. These 
rive classes largely comprise beetle-susceptible material resulting from 
wilt diseases and mechanical damage, such as breakage, girdling, and 
cutting. Trees slowly dying as a result of unfavorable soil conditions 
were found to be only slightly attacked by bark beetles seeking breed- 
ing places. 
A further advantage of this revised program is that it is possible 
to destroy dangerous beetle-infested and susceptible material in certain 
trees by pruning and thus save the tree if it is otherwise a desirable or 
valuable one. Owners of trees have been much more willing to grant 
permission for sanitation work when this has been explained to them. 
During the year field workers eradicated and removed 9,864 elms 
confirmed as infected, 206,540 elms in the sanitation program, and 
56.428 elms in selective operations, a total of 272,832. The grand total 
of trees removed in all operations in the preceding year was 773,604. 
A reduction in the W. P. A. personnel during the winter accounted 
for the decrease. At the end of (lie year a grand total of 5,576,680 
elms had been removed as a result of the various types of operations 
practiced since 1933. There remained standing at the end of the year 
180 diseased trees. 
Selective-cutting operations were performed in the vicinity of 
Cumberland, Md.. to eliminate the elm population in territory for- 
merly scouted with considerable difficulty. Isolated groups of elms of 
low value in rough, mountainous terrain were located and later re- 
moved. Also in Maryland, the removal of beetle-infested elm wood, 
wood furnishing potential breeding places for bark beetles, and dead 
and dying elms was completed within a radius of 4 miles of the soli- 
tary Maryland confirmation. Destruction of wood susceptible to in- 
festation was carried on throughout the winter in the West Virginia 
work area. In Ohio clear-cutting of elms was accomplished wherever 
permissions could be obtained for this type of work in the localities 
where six disease cases were found during the year. Removal of 
