THE HOP PLANT. 59 



of destruction as early as May, and the infested leaves, ex- 

 hausted by suction, are ruined. 



According to the investigations of Eiley and Pergande,^ 

 the aphis lays its eggs, for wintering, on the plum-tree and 

 sloe. 



An advantageous method of treatment is to wash the 

 plants with a 1| per cent, solution of soft soap, containing 

 an addition of tobacco water. Strebel also recommends a 

 li per cent, solution of sapocarbol ; but care is necessary 

 in using this substance, as concentrated solutions stain the 

 leaves and render them sickly. In England (according to 

 Dr. Pott) dilute petroleum, lime water, potash solution, 

 tobacco water, and chlorine water are used, soap solution 

 being, however, the most efficacious. It having been noticed 

 that a copious shower of rain disperses aphides, a thorough 

 drenching of the hops with water alone has been recom'- 

 meuded. Harz advises the rooting up of sloe bushes as a 

 preventive measure. 



The hop louse has a number of natural enemies, which 

 will be mentioned later on. 



12. Haltica concinna, the hop flea, is a small beetle which 

 feeds on the leaves, as does also its larva. The beetle hiber- 

 nates, and in spring time lays eggs from which hatch out 

 small white larvae, which bore into the leaves. The greater 

 damage, however, is done by the beetles eating the leaves 

 into large holes. Occasionally, also, they attack the cones, 

 which then fall into a sad condition and drop off. The best 

 means of destruction is to shake the insects off into sheets 

 cov^ed with tar or brumata glue. 



13. Galocoris vandalicus (Gapsus vandalicus Bossi), the hop 

 b-ug, punctures the tips of the young shoots with its proboscis 

 and kills them off. The adjacent eyes then develop shoots, 



1 C. Pruwirth, Hopfenbau, 1888. 



