48 AX.\l".\l. REPORTS OF DEPARTMENT OE AGRICULTURE, ] 
tr. the plants and the methods cannot be generally recommended on the basis 
of present Information. Observations Indicated thai It is not good practice t<» 
plant corn on newly plowed grassland because of the probable resultant heavy 
infestal Lon. 
Tests of the fungus Sorosporella uveUa against both the Call armyworm and 
the corn earworm were unsuccessful in causing mortality. 
Experiments In control of the corn Leafhopper {Peregrinus maidis Ashm.) 
Indicate that a oicotine dust is of value in reducing the abundance of this pest 
on particularly valuable corn plantings. 
The ortalid fly Euxesta stigmatias Loew was found to be a primary invader 
of corn ears and of considerable importance as a corn pest. Infestations ranged 
from 28 to 92 percent. Although uo special tests were made to devise control 
methods against tins insect, some of the mechanical means utilized against the 
com earworm materially reduced the maggot population. 
INSECTS ATTACKING SMALL GRAINS 
Although extremely heavy infestations of the hessian fly occurred over a 
considerable portion of the Wheat Belt in the fall of 1935 and caused much 
damage, the extremely dry conditions of the following spring and summer pre- 
vented serious damage from the spring brood and reduced the hessian fly 
population to a low ebb. Major emphasis in investigational work has been 
placed on a study of fly reaction to various varieties and strains of wheat, and. 
in cooperation with the plant breeders, on the discovery and development of 
resistant varieties. An attempt is being made to determine the fly reaction of 
all the major commercial varieties of wheat suitable for production under Cali- 
fornia. Kansas, and Indiana conditions. Seventy-live varieties were tested in 
California in the summer of 1935 and .'*<><> varieties of authentic purities are DOW 
under test; ,'J70 varieties, hybrids, and strains are being tested in Indiana and 
375 in Kansas. A variety having almost complete immunity tinder California 
conditions has been discovered and has been successfully carried into the second 
and third back-crosses on commercially desirable club wheats. One variety of 
resistant spring wheat well suited to the soft-wheat region has been discovered 
at Lafayette, Ind., and five others have shown marked resistance and may be 
Of value as lly-resist ant parents in breeding work. In Kansas 13 strains have 
been found tiiat have definite resistance. 4 of which have commercial value. 
Of 400 strains of spring wheat tested at Parsons, Kans.. only '2. besides Mar- 
quillo hybrids, showed resistance to the fly. Certain strains which are resistant 
under California conditions have not retained resistance when grown in In- 
diana. Whether biological strains of the fly or difference in agronomic condi- 
tions are responsible tor this variation is being investigated. Preliminary work 
indicates that soil factors are not involved and that similar variations occurring 
in Kansas probably cannot be explained on the basis of biological strains of 
the fly. It has been quite definitely proved that two factors are responsible for 
resistance in the California selection of Dawson, which has shown most promise, 
although indications are that different genetic factors may be involved in other 
varieties. Numerous colonies of six native and two European parasites of the 
hessian fly have been liberated in various locations in the United States where 
t he\ do not QOW occur. 
The black grain-stem sawfly (Tracheitis tabidus P.) has continued to do much 
damage in western Pennsylvania and eastern Ohio, and the European parasite 
Collyria calcitrator Grav. has been released in both states. Colonies of a 
native parasite, Pleurotropis beneflca Gahan, have also been liberated in Ohio, 
Where it did not pre\ lously occur. 
Winter mortality of the chinch bug was extremely heavy over m08t Of the 
infested area and only scattered outbreaks have occurred in the area included 
in the 1934 epidemic. Some evidence of chinch bug resistance in wheat has 
been obtained and Ls being Studied further. Studies on control of chinch bugs 
by eliminating small grains or by trapping them on barley, which is especially 
attractive, have shown that, while oats are the Least attractive, the elimination 
from :in area of all small grains except o;its would not prevent chimb bug dam- 
age, although Injury might be reduced to some extent. Bven where all small 
grains are eliminated from an area, some Infestations develop directly on corn. 
although a materia] reduction in the general infestation may result No single 
small grain seems sufficiently more attractive than the others to serve effec- 
tively as B trap crop in which the buli of the bUgS in the neighborhood can be 
concent rated and dest royed. 
