﻿THE WESTERN OKN ROOTWORM. 5 



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 1002. both 

 inclusive. 1 



During the years 1011 and 1012 an outbreak of this insect was 

 studied in the Duck River Valley, middle Tennessee, by Mr. George 

 G. Ainslie. In 1013 the same observer found the larva? 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 larva? 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 

 little 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. Ainslie has found the beetles feeding on the 

 leaves of corn and on the pollen of the evening primrose and asters. 



1 Changed conditions that may hare 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 1862 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 crop 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 larvae 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. 



