68 



The Tea insects of India. 



barrels holding about 400 pounds each. That in the cans is much to be preferred, 

 since the qiiantity in each is so small that it will soon be used up after the can is 

 opened ; whereas tbe barrel containing so large a quantity, the cyanide used towards 

 the last will have lost much of its strength by contact with the air. It is customary 

 to weigh out the cyanide in small paper parcels and mark each parcel with the number 

 of ounces of cyanide that it contains : then when the tree is to be fumigated, it is an 

 easy matter for the operator to select one of the parcels containing a sufficient 

 quantity of the cyanide for the tree, thus saving the trouble of weighing out the 

 cyanide as it is ti) be used for each tree. As tiie fumigating is done only at night, 

 the weighing of the cyanide is frequently done by the ladies of the house upon the day 

 preceding its use. 



" The quantity of cyanide to be used on each tree will, of course, depend not only 

 on the size of the tree but also on the strength of the cyanide used. The following 

 table will aid in determining the proper quantity of each ingredient to be used on 

 different-sized citrus trees, the cyanide being about 58 per cent, pure : — 



Height of Tree. 



Diameter of 

 Tree-top. 



Water. 



Sulphuric Acid. 



Potassium 

 Cyanide. 



Feet. 



Feet. 



Pluid OZ3. 



Fluid ozs. 



Ounces. 



6 



4 



1 



h 



k 



8 



6 



2 



1 



1 



10 



8 



H 



'^ 



2f 



12 



10 



8 



. 4 



4 



12 



14 



16 



8 



8 



14 



10 



10 



5 



5 



14 



14 



19 



9| 



9| 



16 



12 



16 



8 



8 



16 



16 



29 



14| 



14| 



18 



14 



26 



13 



13 



20 



16 



36 



18 



18 



22 



18 



52 



26 



26 



24 



20 



QQ 



33 



33" 



HOPPERDOZEUS. 



These appliances have been invented in the United States for the 

 destruction ol; grasshoppers and other active insects which lurk in low 

 vegetation. The value of the crops saved by the use of hopperdozers in 

 the States of North Dakota and Minnesota alone in the year 1890 has 

 been estimated by the Dominion Entomologist of Canada^ at no 

 less than two hundred thousand dollars. Hopperdozers are likely to be of 

 use upon Indian tea gardens, not only for destroying grasshoppers in 

 the weeds about the tea bushes, but also for catching such insects as 

 the active larvse of the mosquito blight which drop off the bushes 

 when disturbed. 



The forms in use in the United States vary a good deal in construc- 

 tion. The essential feature in each case, however, consists of an open pan 



(*) See his address to the Association of Economic Entom-.logiets, Washington, 1891. 



