174 



THE AMEEICAN ENTOMOLOGIST. 



infested by Chinch Bug than wheat put in upon 

 land tliat has been ploughed. There is another 

 fact which has been repeatedly noticed by prac- 

 tical men. This insect cannot live and thrive 

 and multiply in land that is sopping with 

 Avater ; and it generally commences its opera- 

 tions in early spring upon those particular parts 

 of every field where the soil is the loosest and 

 the driest. 



There are, as is well known to Entomologists, 

 many genera of the Half-winged Bugs, which in 

 Europe occur in two distinct or " dimorphous " 

 forms, with no intermediate grades between 

 the two; namely, a short-winged or sometimes 

 even a completely wingless type and a long- 

 winged type. Frequently the two occur pro- 

 miscuously together, and are found promis- 

 cuously copulating so that tliey cannot possibly 

 be distinct species. Sometimes the short- 

 winged type occurs only in particular seasons 

 and especially in very hot seasons. More 

 rarely the short-winged type occurs in a differ- 

 ent locality from the long-winged type, and 

 usually in that case in a more northerly locality. 

 We have a good illustration of this latter 

 peculiarity in the case of the Chinch Bug, of 

 which we received eleven specimens (Fig. 122) 

 [Fig. 122.] some years ago from Can- 



ada "West, that unques- 

 tionably are a dimorph- 

 ous short-winged form of 

 the normal long-winged 

 form found so abundantly 

 in the Western States. 

 So far as we are advised, 

 it has never occurred in 

 such numbers in Canada 

 as to do any damage there ; 

 neither is such an event 

 probable, because, as al- 

 ready stated, the Chinch 

 Bug is decidedly a Southern species and does 

 not flourish even in NewEngland and New 

 York. 



Natural Checks to the Multiplication of the 

 Chinch Bug. 



It will be asked why Chinch Bugs do not in- 

 crease every season, with the same frightful 

 rapidity and at the same terrific rate of Geomet- 

 rical Progression, that has been referred to 

 above. The answer is simple. They are cjiecked 

 in their increase in certain years by two causes, 

 first, the prevalence of frequent heavy show- 

 ers, and second, by being themselves preyed on 

 by several carnivorous or cannibal insects and 



to a certain extent by birds. We will now dis- 

 cuss the first branch of this subject, and after- 

 wards take up the second. As to the popular 

 idea, that cold winters kill this and other nox- 

 ious insects, we do not believe that there is any 

 truth in it. You may take any large wood- 

 boring larva and expose it to a temperature of 

 many degrees below zero, till it freezes as solid 

 as an icicle ; and yon may then take it into a 

 warm room and thaw it out, and it will be as 

 brisk and as lively as ever. It is very true that 

 it requires a very low temperature to freeze such 

 a larva — probablj^ for the same reason that gum- 

 water will not freeze at aiiy ordinary tempera- 

 ture — but still freezing, even if repeated several 

 times, does not seem to injure its vitality in the 

 least. As a general rule, we believe that it is 

 only extremes of drought and moisture, and not 

 extremes of heat and cold, that affect insects in- 

 iuriously. Some of the very worst summers for 

 noxious insects have followed very cold winters. 



Heavy Rains destructive to the Chinch Bug. 



As the Chinch Bug, unlike most other true 

 Bugs, deposits its eggs underground, and as the 

 young larvse live there for a considei'able time, 

 it must be manifest that heavy soaking i-ains 

 will have a tendency to drown them out. The 

 simple fact, long ago observed and recorded by 

 practical men, such as Mr. B. E. Fleharty of 

 North Prairie, Knox county. Ills., that this in- 

 sect scrupulously avoids wet land, proves that 

 moisture is naturally injurious to its constitu- 

 tion. Hence it was many years ago remarked 

 by intelligent farmers, and we have ourselves 

 repeatedly observed the same thing, that very 

 often when the spring opens drj^ Chinch Bugs 

 will begin to increase and multiply in an alarm- 

 ing manner; but that the very first heavy 

 shower checks them up immediately, and re- 

 peated heavy rains put an almost entire stop to 

 their operations. It is very true that nearly all 

 insects will bear immersion under water for 

 many hours, and frequently for a whole day, 

 without suffering death therefrom ; for although 

 animation is apparently suspended in such cases, 

 they yet, as the phrase is, "come to life again." 

 But no insect, except the few that are provided 

 with gills like fishes and extract the air out of 

 the water, instead of breathing it at first hand, 

 can stand a prolonged immersion in water with- 

 out drowning. And it must be obvious to the 

 meanest capacity, that an insect, such as the 

 Chinch Bug, whose natural home is the driest 

 soil it can find, will have its health injuriously 

 affected by a prolonged residence in a wet soil. 



