184 



STATE BOARD OF AGRICULTURE. 



REMEDIES. 



The treatment is the same as that for the hop-merchant. 



Hop-louse {Phorodon humuli). 



Fi^. 34. — Hop-merchant, after Dr. L. O. Howard, Bui No. 7, 

 N Scr . Bureau of Entomology, U. S. Dept. of Agriculture. 



REMEDIES. 



Such a fragile creature 

 as an aphid can hardly 

 hope to pass the winter 

 successfully on such a 

 plant as the hop which is 

 spread on the ground dur- 

 ing the cold season. For 

 this reason, a curious 

 habit has been developed. 

 Late in the season, wing- 

 ed sexual forms are de- 

 veloped from the non- 

 sexual form of the lice 

 that have been feeding on 

 the hop all summer, and 

 these sexual forms lay 

 their eggs on the plum 

 trees, where the eggs are 

 in good high situations, 

 safe for the winter ex- 

 cept from birds and other 

 enemies. In the spring, 

 wingless forms are pro- 

 duced at first, and from 

 these, winged females 

 which migrate to the hop 

 to become the parents of 

 the myriads of lice which 

 later appear. 



The lesson to be learned from this life-history is very easy to see. 

 Avoid having plum trees, either cultivated or wild, near the hop yards. 

 If it is imp(jssible to do this, then s])ray the plums with kerosene-emul- 

 sion, or tobacco-water just as soon as the eggs hatch, and spray with 

 extreme care so as to hit as many of the lice as possible, before they 

 migrate to the hops. 



It will be necessary, in many cases, to spray the hops themselves, 

 especially the vines on which the lice first appear, and which serve as 

 centers of infestation for the rest of the field. 



Kale (see Insects Affecting Cabbage). 



