


THE WESTERN CORN ROOTWORM. . 5 
e 
It has been thus the writer’s good fortune to follow personally the 
destructive spread (though not the actual diffusion) of the species 
throughout three States and from the years 1874 to 1902, both 
inclusive.? , 
During the years 1911 and 1912 an outbreak of this insect was 
studied in the Duck River Valley, middle Tennessee, by Mr. George 
G. Ainslie. In 1913 the same observer found the larve attacking 
corn in the bottom lands of the Tennessee River about Chattanooga, 
Tenn. | 
The pest appears to be making its way into and throughout the 
bottom lands of rivers flowing through the Southern Atlantic and 
Gulf States, precisely as it has been observed to do in Indiana and 
Ohio. 
DIFFICULTY IN DETECTING INJURY TO CORN. 
As will have been noted, the work of the larve is very obscure and 
few farmers are likely to detect them at work in the roots during 
June and July, while it would be simply impossible for the farmers, 
even if they did discover them, to connect them definitely with the 
hitle green beetles that swarm in the silk of the ears during summer 
and early-fall. 
FOOD OF THE BEETLES. 
In the cornfield the food of these beetles is made up of corn silk 
and pollen. Rarely do they eat of the unripe kernels at the tips of 
the ears, and then only when birds have previously pecked into these 
kernels. Outside the cornfields the writer has found them in the 
blossoms of thistle, sunflower, goldenrod, cucurbits, cotton, clover, 
and rose, and on the leaves of cucumber and beans, while the species 
has been reported to him as eating into ripe apples where the skin 
had been previously ruptured by other causes. Dr. Forbes has found 
spores of fungi and pollen of smartweed in their stomachs. More 
recently Mr. George G. Ainshe has found the beetles feeding on the 
leaves of corn and on the pollen of the evening primrose and asters. 

1Changed conditions that may have caused a change of habit in the insect.—As the 
writer well remembers, the principal crop in many portions of Illinois, especially through- 
out the prairie country, up to 18652 was spring wheat. Influences of the Civil War at 
that time brought the price of pork up to a point where its production became a most 
profitable occupation for the farmer. At the same time wheat growing declined rapidly, 
the acreage being devoted to corn in order to afford food for the increasing number of 
hogs. In those days ecrep rotation received scant attention from the ordinary farmer, 
and corn was more often than otherwise planted year after year on the same ground 
How soon it was, after this change in the principal crop from wheat to corn, that these 
beetles, attracted to the cornfields perhaps by the enormous amount of pollen found 
there as well as by the equally inexhaustible food supply offered by the silk, began to 
deposit their eggs and develop in these fields, it is not possible to say. We do know, 
however, from the records already given, that injuries from the larve began to be noticed 
in 1874, about 10 or 12 years after this change in production of wheat and corn took 
place, thus giving us at least a clue to the primary causes which seem to have changed 
the food of the insect to a cultivated crop. 
