43 



the (irst liir\;i of an Aiiicricaii luirsctly was dcscribt'd more thau 

 tliirty vi'ai-s a^^). and that since that time many economic ento- 

 inoloirists in all pacts of the country have been investigating 

 all irijinncr- of sul).i('cts willi which insects are concerned, we 

 hardly know how to explain the fact that so little is really 

 known about these stages. 



If all species were alike in their habits, a knowledge of the 

 immature stages of one species would make it an easy matter 

 to work oiit the life histories of the others. The fact that so 

 few have been worked out is proof in itself that all species are 

 not alike: and when one undertakes the study of a particular 

 species, in addition t() those with which he already claims an 

 ^.e(piaintance, he is not only convinced that the immature stages 

 •of two species may be different, but that they may have scarcely 

 a single habit in common. 



lIorseHies are a recognized pest in all parts of the world, 

 and although it is difficult to estimate the damage done by them, 

 every farmer and stock-raiser admits it to be considerable. It 

 is a fact that all remedies that have been suggested are unsatis- 

 fact(»ry in a measure, but it is quite possible that by continued 

 «tudy and investigation of the problem effective remedial meas- 

 ures may be developed. 



