18 SECOND ANNUAL REPORT OF 



been dry and favorable to the increase of this, the greatest insect foe 

 of the wheat-grower. 



We may safely conclude that the Chinch Bug has always existed 

 in Missouri, in small numbers; but that it did not multiply to an in- 

 jurious extent until the grains began to be cultivated on an exten- 

 sive scale. At all events, we know from the evidence of Dr. Harris 

 and Dr. Fitch, that it existed long ago in exceedingly small numbers 

 in New York, and even in Massachusetts. What the causes may 

 have been, that thinned out the numbers of this insect in former 

 times in the West, is another question. In former times, the great 

 bulk of these bugs were probably destroyed every winter by the 

 prairie fires, and, as cultivation has extended in consequence of the 

 country being gradually settled up, and less and less prairie has been 

 annually burnt over, the number that has survived through the win- 

 ter to start the next year's broods has annually become greater. If 

 these views be correct, we may expect them, unless more pains be 

 taken to counterwork and destroy them, to become, on the average 

 of years, still more abundant than they now are, whenever prairie 

 fires shall have become an obsolete institution ; until at last West- 

 ern farmers will be compelled, as those of North Carolina have 

 already several times been compelled, to quit growing wheat alto- 

 gether for a term of years. 



It may be very reasonably asked, why the Chinch Bug does not 

 increase and multiply in Massachusetts and New York, seeing that it 

 existed there long ago, and that there are, of course, no prairie fires 

 in those States to keep it in check. The answer is, that the Chinch 

 Bug is a Southern, not a Northern species ; and that hundreds of 

 Southern species of insects, which on Hhe Atlantic seaboard only 

 occur in southerly latitudes, are found in profusion in quite a high 

 latitude in the Valley of the Mississippi. The same law, as has been 

 observed by Professor Baird, holds good both with Birds and with 

 Fishes.* 



NATURAL HISTORY OP THE CHINCH BUG. 



In the four great and extensive Orders of Insects, namely, the 

 Beetles (Colcoptera), the Clear-winged Flies (Hi/menoptera), the 

 Scaly-winged Flies (Zepidopter'a), and the Two-winged Flies (Dip- 

 tt ,v/), and in one of the four small Orders in its restricted sense, 

 namely, the Net-winged Flies (Neuroptera), the insect usually lies 

 still throughout the pupa state, and is always so far from being able 

 to eat or to evacuate, that both mouth and anus are closed up by 

 membrane. In the remaining three small Orders, on the contrary, 

 namely, that of the Straight- winged Flies in its most extensive sense 

 ( Orthoptera including Pseudo-neuroptera), the Half- winged Bugs 

 (IL'teroptera) and the Whole-winged Bugs (Jlomoptera), the pupa is 

 just as active and just as ravenous as either the larva or the perfect 



* Silliiaan's Journal, xli, p. 87. 



