698 



REPORT UNITED STATES GEOLOGICAL SURVEY. 



harvest I was not able, with the most diligent search, to fiud one. At 

 harvest I did succeed iu finding a few in some localities." Tbis disease 

 among the chinch-bugs was associated with the long-continued wet, 

 cloudy, cool weather that prevailed during a greater portion of the 

 period of their development, and doubtless was in a measure produced 

 by deficient light, heat, and electricity, combined with an excessive hu- 

 midity of the atmosphere." In 18GS it again, according to the editors of 

 the American Entomologist, "did considerable damage in certain 

 counties in Southern Illinois, and especially in Southwest Missouri." 

 In 1871 Dr. Le Baron estimates the losses to corn and the small grains 

 in the Northwestern States at $30,000,000, and Riley estimates the loss 

 in 1874 in the same area as double that sum, the loss in Missouri alone 

 being $19,000,000. Apparently no injury was sustained in Colorado in 

 1875 from this insect. 



In the accompanying map showing the distribution of the chinch-bug, 

 I have been mainly dependent on the statements of the State and other 

 entomologists of the West, and the reports of the Agricultural Depart- 

 ment. I have found the insect on the summit of Mount Washington, 

 and argue from this fact that it is widely distributed over the colder as 

 well as warmer portions of the New England States. It probably in- 

 habits the entire United States east of longitude 100°, and will proba- 

 bly occur in the Western Territories, wherever wheat is raised, though 

 perhaps the altitude and peculiar climatic features of the Rocky Mount- 

 ain Plateau may prevent its rapid and undue increase. 



Egg, young and adult. — The egjr is minute, oval, 0.03 inch long, four times as long as 

 broad, and white. The larva is at first pale yellow, afterward becoming red, changing 

 with age to brown and black, and marked with a white band across the back. The 

 adult is armed with a powerful beak, instead of jaws, with which it punctures the stems 

 of iilants and sucks iu the sap ; it sometimes abounds to such an extent as to travel in 

 armies from field to field ; it may be known by its white fore wings, contrasting well 

 with a black spot on the middle of the edge of the wing, and is about three-twentieths 

 of an inch in length. Certain individuals have very short wings. 



f 



Fig. 4. — Adult and immature stages of Chinch-Bng.— «, h, eggs; c, newly-batched 

 larva ; d, its tarsus ; e, larva after first molt ; /, same after second molt ; g, pupa — the 

 natural sizes indicated at sides ; 7(, enlarged leg of perfect bug; j, tarsus of same stiU 

 more enlarged; i, proboscis or beak, enlarged. (After Riley.) 



Remedies. — Burn stubble, old straw, and corn-stalks among weeds in 

 fence-corners in the early spring. Riley advises the early sowing of 

 small grain in the spring, and suggests that the harder the ground is 

 the less chance there is for the chinch-bug to penetrate to the roots of 

 the grain and lay its eggs thereon. " Hence, the importance of fall- 

 plowing, and using the roller upon land that is loose and friable." 

 Heavy rains and cold, damp seasons reduce its numbers materially. 

 Where irrigation is practiced, fields may be flooded for several days in 



