BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 39 
These cultures were made from individuals collected in the field in Virginia, 
in April before corn was planted, and the insects apparently had carried the 
infection over winter. 
CORN EARWORM 
The summer of 1934 was marked by one of the most severe and general out- 
breaks of the corn earworm ever recorded. From Ohio on the east to Iowa 
and Nebraska on the west and from Minnesota southward to Arkansas the 
insect wreaked havoc with the corn crop. In Iowa alone the loss to corn was 
estimated to have been at least 10 percent of the crop. Other crops, such as 
tomatoes, were severely injured throughout this region. 
For several years limited investigations have been conducted in an effort to 
obtain practical control of this pest in corn. These studies have been inten- 
sified and expanded and a full program has been set up with a view to deter- 
mining fundamental facts regarding the insect, including the geographic limi- 
tation of hibernation. Some 13 observation stations, located from Kansas 
and Nebraska eastward to the Atlantic coast and as far north as Connecticut, 
have been established for this purpose. At four of these stations, located in Vir- 
ginia, Missouri, Indiana, and Kansas, respectively, intensive observations on 
all phases of the behavior of the insect are being carried on. Included in this 
program are investigations of resistant strains of corn, control through insecti- 
cides, and the utilization of variation in farm practice or cultural control. 
INSECT PESTS AFFECTING THE MILLING INDUSTRY 
During the year it was demonstrated that, contrary to common belief, the 
eggs and young larvae of the flour beetles pass unharmed through the milling 
process. This indicates that infested grain and infested clear and low-grade 
flours fed into the product for blending constitute the most important sources 
of infestation for flour in the mills. 
The relative efficiency of the several standard fumigants used to protect 
stored grain has been determined. The perfection of a method of applying 
one of these, viz, hydrocyanic acid gas. to milling equipment has resulted in 
lower costs for fumigants, increased efficiency, reduced labor charges, reduc- 
tion in loss of running time, and elimination of loss because of stock ordi- 
narily removed from milling machinery and sold as stock feed. 
EUROPEAN CORN BORER INSPECTION AND CERTIFICATION 
Issuance during the fiscal year of 16,184 certificates for commodities re- 
quiring Federal certification to meet the requirements of State quarantines 
or orders on account of the European corn borer (Pyrausta nuMlalis Him.) was 
an increase of 55 percent in the number of certificates required in the same 
territory during the previous fiscal year. Articles covered by these certificates 
had an estimated value of $186,391. This sum is 83 percent greater than last 
year's estimated valuation of certified commodities. With the exception of 
November 1934, when the number of certificates issued approximated that of 
the previous year, the monthly certificate requirements uniformly exceeded 
those of any previous month since reorganization of the Federal corn borer 
inspection service in January 1933. Stimulated sales of roots and plants 
of dahlia largely occasioned the demands for this type of inspection and 
certification. 
State European corn borer quarantines or orders necessitating maintenance 
of a Federal inspection service remained unchanged during the year. Entry 
of likely carriers of the corn borer from infested Stales into Arizona. Cali- 
fornia, Colorado, Georgia, Louisiana. Nevada. Oregon, Tex,.-, and Utah was 
still conditioned on Federal inspection and certification. 
Few of the State quarantine orders were revised or reissued during the 
year. In a revision effective January 15, 1934, the Nebraska State quarantine 
was changed to eliminate celery, oat and rye Straw, cosmos, zinnia, and 
hollyhock from the articles under regulation. Restrictions formerly imposed 
by the Nebraska quarantine on the movement of vegetable and flora] plants 
from Indiana, Michigan, and Ohio were also eliminated. A supplement 
to Colorado European corn borer quarantine no. 4. effective May 1, 1935, 
permitted entry into Colorado until July 1. 1935, of cornstalks and fodder 
when sweetened and processed in hammer mills approved by inspectors of this 
Bureau. The State of Illinois on May s, 1935, modified its corn-borer quar- 
antine to permit admission into thai State of green sweet corn and corn 
