CHAPTER X 



PESTS OF THE HOP CROP. 



[ i'lic 111 illrr on Insecl.s affeetiii^^ tin? liop i>laiit, tip to Page 141, -vras 

 wn.i.ii i.,i- II, IS work hy L. (). llowuril, llj, D., Eiitomoloijist United 

 biates Departnieiit of AgriculUirt'.] 



SIDE from the damage done 

 by the hop plant louse in oc- 

 casional seasons, and a 

 rather infrequent period of 

 abundance of the so-called 

 "hop grub," the hop crop in 

 the United States does not 

 suffer seriously from the at- 

 tacks of insects. The abun- 

 dance of plant lice in gen- 

 eral, with this species as 

 with others, bears a direct relation to the weather, in 

 that when the precipitation exceeds the normal, the 

 lice are apt to be more abundant, whereas in dry sea- 

 sons they almost entirely disappear. The same law 

 also holds as to localities, and this doubtless accounts 

 for the fact that the hop crop in England suffers more 

 tmiformly from lice than it does in central Xew York. 

 The causes of the occasional al)undance of the grub 

 and of the other less important insects are not so read- 

 ily determined. 



Nearly all of the hop insects of the United States 

 are native to this country and feed upon other allied 

 plants of the family Urticaccac. The hop plant louse, 

 however, is an exception and is of European origin, 

 while there are one or two other European insects of 

 some importance which feed upon this crop which may 

 yet be introduced into the United States. 

 8 113 



