PROGRESS REPORT ON THE EUROPEAN CORN BORER 141 
responsible for the death of the larvae is not known. In breeding- 
cages several species of spiders have interfered with the experiments 
by attacking and killing migrating larvae, and occasional occur- 
rences of a similar nature have been recorded in the field. 
DISEASE 
Occasionally, both in the field and in confinement, nearly full- 
grown larvae have been found during the summer and fall which 
apparently had succumbed to a disease resembling bacterial wilt. In 
the breeding cages at Silver Creek. N. Y., the rearing work was 
seriously hampered because of the mortality due to this disease. 
Specimens of larvae which had died, apparently from this disease, 
were submitted to G. F. White and A. T. Speare of the Bureau of 
Entomology, who reported that they were unable to find any pro- 
tozoa, fungi, or polyhedral bodies in the samples submitted, but that 
an undetermined bacterium was present in great numbers. Later 
an attempt to isolate the causative organism was made by H. AY. 
Allen of the Arlington, Mass., laboratory, in cooperation with R. W. 
Glaser of Bussey Institution, but the results were negative. Since 
only a comparatively small number of larvae have been killed by it in 
the field, this disease is evidently not important enough to be of ma- 
terial benefit. 
CONTROL AND QUARANTINE 
CONTROL 
The details relating to the control, quarantine, and scouting 
phases of the European corn-borer activities will be given in a 
separate publication and may be summarized briefly as follows : 
From the fact that the insect passes the greater part of its larval 
stage and its entire pupal stage within the host plant, thus afford- 
ing but little chance for insecticidal or other remedial measures 
under large-scale field conditions, it is evident that the major con- 
trol efforts should be directed toward cultural practices leading to 
the utilization or the destruction of infested plants, particularly by 
feeding to livestock, burning, or plowing under; supplemented by 
preventive agronomic adaptations in the culture, of corn, particularly 
the selection of varieties least susceptible to severe injury, combined 
with the regulation of the time of planting these varieties to escape 
serious infestation and yet produce satisfactory yields. None of 
the insecticides tested can be recommended for general use, although 
nicotine dusts containing 2 or more per cent of free nicotine directed 
against the newly hatched larvae have given encouraging results 
in limiting injury to valuable crops of corn. The possibility of 
developing more effective treatments is still under investigation. 
YTien considering general control measures for the corn borer it 
is necessary to make proper allowance for the fact that two genera- 
tions occur annually in the New England area and that in this 
area the insect infests commonly a great variety of plants, including 
corn, vegetables, flowers, field crops, and large-stemmed grasses and 
weeds; whereas in the western areas, including New York. Penn- 
sylvania, Ohio, and Michigan, the corn borer is single brooded and 
is confined principally to corn. In New England, therefore, it is 
necessary to utilize or destroy all plants or crop residues which 
are listed as hosts of the corn borer, and in the middle western area 
