58 



ravages of this insect \\n\v aiiiouiitod in single states to from ten to 

 twenty million dollars in a season, and throughout the whole range of 

 the insect to a huiulretl million dollars or more in a single year. 



It must be admitted, however, that the weather conditions under 

 which its injuries become serious are such that the corn would suffer 

 materially from drouth if it were not infested by chinch-bugs at all, and 

 as the effect of the insect attack is vii-tually indistinguishable from that 

 of excessive dry weather, it is usually quite impossible to separate the 

 effects of these cooperating causes. Estimates of injury by chinch-bugs 

 are therefore exceptionally uncertain. 



Descriplion of the Chinch-hug. — Although tliis insect is so abuiulant 

 and destructive at certain times and places, its appearances in numbers 

 sufficient to attract attention are often separated by intervals o" many 

 years, and multitudes of farmers consequently do not know it at sight. 



When fully grown (see Plate I) it is readily distinguished from 

 other insect of its region by its size and form, and by the peculiar distri- 

 bution of the white on its back. Looked at from above, the outline of 

 the entire insect is an elongate oval with rather straight sides and 

 broadly rounded ends. Its length is three twentieths of an inch or a 

 little less, and its breadth about a fomih as much. The head and 

 thorax are black, and all the surface is minutely hairy except that of the 

 wings, The wing-covers, which conceal the abdomen, are milk-white, 

 with a triangular black scutellum between them in front, and a black 

 blotch at about the iniddh* of each side. These invasions of the white 

 area give it roughly \\\v form of the letter X, and this cross mark of 

 white on the back is the characteristic mark of the species. In winged 

 specimens which have recently changed by molting from the jireceding 

 stage, the black of the above descrijition is represented by a dull pink, 

 the wing-covers, however, being wholly white, with pinkish veins. 



The chinch-bug molts four tinu^s tiftcr hatching, and changes its 

 appearance materially with each molt. There are thus five distinguish- 

 able stages, the first three of which together are often called the red 

 stage of the insect. 



In the first of the red stages the young (•hiiu"h-l)ug is pale red tlu\)ugh- 

 out, with a band t)f yellowish across the base of the abdomen. 



In the second stage the red of the head and the prothorax changes to 

 a dusky tint, and the abdomen becomes a bright vermilion with a pale 

 yellow band across its base, and with faint dusky patclu^s on its poste- 

 rior segments. 



In the third stag(\ small rounded pads appear on the thorax, pro- 

 jecting backward in the place of thi^ future wings. The head and the 

 thorax are wholly black or dusky, and the abdomen is a dusky red with 

 a patch of darker red near the miildle. the light band across its base still 

 remaining, although partly conceak\l by the wing-pads at its ends. 



