59 



In the fourth stage the original red color has wholly disappeared, 

 the general tint varying from dusky gray behind to black in front, with 

 a remnant of the pale band across the base of the abdomen showing 

 behind the much enlarged wing-pads. This is sometimes called the pupa 

 stage, and is, of course, the next preceding that of the winged insect. 



The egg (see PI. 1) is a very slender oval, about .03 of an inch in 

 length, rather narrowly rounded at one end, and slightly docked or 

 squared at the other, where, under a high magnification, four small 

 rounded tubercles may be seen. Its cxAor is at first whitish and trans- 

 lucent, but later darkens to amber, and finally, as the insect develops 

 within, becomes definitely red. 



Food Plants and Injuries to Crops. — The chinch-bug injures all the 

 grasses and cereal crops, but is strictly limited for Food to plants belong- 

 ing to the grass family and to cei-tain wild sedges. It is most destruc- 

 tive to wheat, and next, probably, to corn, although it is likely to damage 

 oats very severely. It infests the meadow and pasture grasses generally, 

 and may destroy tlunn as completely as any other crop; but owing to 

 their pereimial growth they afford in spring much less fresh and succu- 

 lent herbage than tlie young and delicate; ])lants in fields of corn and 

 wheat. Where spring and winter wheat are grown in the same region, 

 the chinch-bug is more likely to destroy the former, mainly because 

 spring-sown grain is exposed for a longer time to chinch-bug attack 

 before it is harvested. The chinch-biig never injures clover, the cow- 

 pea, or any forage crop which would not commonly be recognized as 

 grass; neither does it injure potatoes, beans, or fruiting [)lants of any 

 description. 



There is probably never a year in which the chin(;h-bug does not 

 injure grass or some cereal in some part of its territory. It is, however, 

 subject to very wide fluctuations in nimiber, boconiing at irregular 

 intervals a pest of such frightful character as to appall the agriculturist 

 and reduce whole districts to temporary poverty. It has, indeed, 

 modified in inifjortant ways the agricultiu'e of large sections of our 

 country, leading to the permanent abandonment of wheat culture in 

 many counties of Illinois, and forcing in others the use of leguminous 

 forage plants in place of the grasses and a substitution of orchard (mlture 

 for the raising of grain and grass. 



There is no very definite regularity in the recurrence; of its [)eriods 

 of greatest destruction. These are, however, clearly dependent on the 

 periodicity of the weather, injury by the chinch-bug reaching its maxi- 

 mum after several dry years, and being suspended by the occurrence of 

 two or three wet years in succession. 'I'lie cliinch-bug period is, how- 

 ever, less definite and tangible than the weather i)eriod, since not every 

 such change in the weather is followed by a notable corresponding (change 

 in the chinch-bug situation. The rise and the fall of a wave of chinch-bug 



