109 



(Fig. 27.) The hop plant louse, true sexual female. (Enlarged.) 



From the life liistory just given, three important facts are obtained. (1.) 

 It will pay to make a preveutive application of some of the mixtures men- 

 tioned further on, with apparatus before described, to all plum trees in the 

 neighbourhood of hop yards, either in the spring, before the appearance of the 

 first winged generation and its consequent migration to hop, or in the fall after 

 hop picking and after the lice have once more returned to the plum, and are 

 making their preparations for the laying of winter eggs. The latter time 

 will, perhaps, be preferable, for the reason that in the fall the plum trees will 

 be less susceptible to the action of the washes, and a stronger solution can be 

 applied without danger to the trees. (2.) All wild plum trees in the woods 

 through a hop-growing country should be destroyed. (3.) The hop vines should 

 be either Inirned or thoroughly drenched with kerosene emulsion as soon after 

 the crop is harvested as possible, with a view of killing tJie males, and thus 

 preventing the impregnation of the females. (4.) If the above measures have 

 been neglected and the lice have attacked the vines, the crop can still be 

 protected by spraying with insecticide mixtures, which if thoroughly applied 

 will prove effective, and there will be no danger of reinfestation from neigh- 

 bouring untreated yards, since during the summer the lice cannot migrate 

 except by crawling from one yard to another, 



Mr. Chas. Whitehead, F.S.A., etc., etc., Agricultural Adviser to the Frivy 

 Council, says in reference to the formula given below : " There are no actual 

 proofs that any other remedy or treatment than washing is at all effectual 

 against the aphis blight. Lime has been thrown up over the plants without 

 any results. Soot has been tried. Insecticides are dead failures, and man- 

 uring has had no marked influence." 



The following formula for a S])ray is recommended by the Board of 

 Agriculture of England and is found to be most effectual : A decoction of 10 

 lt)s. of quassia chips made by boiling ; 7 IDs. soft or whale-oil soap, and 100 

 gallons of water. The chips may be used twice, the second decoction being of 

 course weaker. The hops should be sprayed at least five times during the 

 summer, and if the insects are very bad, oftener. 



