The Tea insects of India. 



the case of plum trees, and one ounce to twenty gallons of water in the 

 case of apple trees. 



The precise strength, which it is desirable to adopt in each case, can 

 only be ascertained by experiment. It should be remembered, however, 

 that mature foliage will always stand a stronger wash than young 

 shoots, and that, as the full effect of the poison is not always observable 

 until three or four days after the application has been made, it is better 

 to err on the side of making the mixture too weak rather than too strong 

 at first. 



Whether, upon the whole, London purple or Paris green is the better 

 agent to adopt for general use in India, is a question which it is difficult 

 to decide upon the evidence at present available. Both have their ad- 

 vocates, and the circumstances under which it will be found preferable to 

 apply one rather than the other can only be ascertained absolutely by 

 experiment. 



Pyrethrum. ' 



This preparation consists of the ground-up petals of the flower of 

 Fyretlirum cineraria foUmn. It is largely used for domestic purposes 

 and can also be employed for the destruction of caterpillars in the open. 

 It has the great recommendation of being harmless to animals other than 

 insects, but is unfortunately too costly for general use, under ordinary 

 circumstances, in the field. The following extract from Note& on Econo- 

 mic Entomology , Calcutta, 1888, gives the necessary particulars about 

 its application : — 



" Fyrethrum cineraricBfolium, a plant native to Dalmatia, has long been known to pos- 

 sess insecticide properties, especially in the powder from the dried and pulverised flowers. 

 The species has proved to be hardy throughout the greater part of the United States, and 

 Mr. Milco of St on, California, has for some years cultivated it extensively with con- 

 siderable profit, the product being sold under the name of " Buhach." The insecticide pro- 

 perties reside in a volatile oil. It acts only by contact, and its action on many larvae is said 

 to be wonderful, a minute quantity in time paralysing and ultimately killing. Its influence 

 in the open air is evanescent, in which respect it is far inferior to the arsenical products ; 

 but being perfectly harmless to plants, it can frequently be used on vegetables where more 

 poisonous substances would be dangerous. 



" Pyrethrum is supposed to have no effect on the higher animals. Dr. Riley's experi- 

 ence, however, is that fumes in a closed room have a toxic influence, intensifying sleep 

 and inducing stupor ; while the experience of Professor Bell with the powder copiously 

 rubbed on a dog, showed that the animal was made sick and was affected in the locomotive 

 organs very much as is the case with insects. 



" The pulverised flowers are sold at about fifty cents per pound in America. The best 

 method of using being to pour a quart of alcohol on a pound of the powder; leave it to 

 stand for an hour and mix VFith forty or fifty gallons of water to be applied with a San Jose 

 nozzle, or better to let the alcohol simply percolate through the powder and thus obtain 

 a clear tincture, which can be applied with any nozzle. The powder may also be applied 

 with bellows or mixed with water and applied by a pump." 



