14 



THE GREATER WHEAT STRAW- WORM. 



{Isosoma (jrande Riley. Fig. 3, form yiiinutn; fig. 4, forui (jrcmde.) 

 PREVIOUS RECORD OF THE INSECT. 



The history of this species extends back onl}^ to 1880, though it was 

 probably for maii}^ years confused in wheat with the joint-worm. 

 It sometimes occurs that insects which the systematist can only con- 

 sider distinct prove on thorough study to belong* to one and the same 



Fig. 3. — Greater wheat straw-worm {Isosoma tjrande Riley), spring generation, form minutuw: a, b, 

 larva; /, female; ;/, fore-wing; h, hind-wing; all much enlarged (from Riley). 



species, while, on the other hand, it sometimes occurs that what the 

 systematic entomologist considers the same species prove on investi- 

 gation to be entirely different, and thus the problem of control, if 

 injurious, is either simplified or complicated, as the case may be. 



However easy it may 

 appear to the farmer, 

 to learn all of the life 

 history of an insect is 

 not unfrequently a 

 matter of no little dif- 

 lic ult}' . W here we can 

 follow out the life C} cle 

 of a species accurately, 

 there is usually found 

 some place or period 

 in its existence when 

 it is more easily con- 

 trolled or destroyed 



Fig. 4.— Greater wheat straw-worm {Isosuma grande Riley), adult ^[^g^jj {^^ anv other time 

 summer form, much enlarged (from Howard). t -i cj_ ' ^.i. j. 



and it often occurs tnat 

 at the critical point some simple manipulation of his land or his crop, 

 on the part of the farmer, will accomplish wonders. This species 

 seems to offer illustrations of all of these features. 



