The Tea insects of India. 



" A tent 26 feet tall by 60 feet in circumference — a size large enough to cover the 

 largest orange tree now growing in this State — if made out of drilling, and either 

 painted or sized, as described above, will cost completed about 60 dollars. Where the 

 trees to be treated are not more than 12 feet tall, the tent can be placed over them by 

 means of poles in the hands of three persons ; to atcomplish this, three iron rings are 

 sewed to the tent at equal distances around, and 6 or 7 feet from the bottom of the 

 tent ; immediately under each of these lings an iron hook is attached to the lower 

 edge of the tent. When the latter is to be placed ever a tree, each of the hooks is 

 fastened into the corresponding ring above it ; one end of a pole is then inserted into 

 each of these rings, and the tent is raised and placed on the tree. The hooks are then 

 released from the rings and the lower edge of the tent allowed to drop upon the 

 ground. 



" Instead of allowing the tent to rest directly on the tree, some growers use an 

 umbrella-like arrangement, the handle of which is in two pieces, which are fastened 

 together with clamps provided with pins ; this allows the handle to be lengthened or 

 shortened according to the height of the tree. This apparatus is put up over the tree, 

 and the tent allowed to rest upon it. By the use of this simple device the danger of 

 breaking off the small twigs on the upper part of the tree by the weight of the tent is 

 avoided. Mr. Leslie, of Orange, used four tents and tent rests of this kind, and he 

 informs me that with the aid of two men he fumigated 120 trees in one night. To 

 remove the tent from one tree, place it over another, and charge the generator required 

 only one minute and a half. In the place of poles some persons attach a circle of gas 

 pipe to the lower edge of the tent ; then two men, each taking hold of opposite sides 

 of this circle, threw the tent over the tree. Dr. J. H. Dunn, of Pomona, informs me 

 that four men, using sis tents like the above, fumigated 240 orange trees in one night, 

 and that the average for each night was over 200 trees, the latter being 8 feet or less 

 in height. After the tent is placed over the tree, the next step is to charge it with the 

 gas. The materials used for the production of the gas consist of commercial sulphuric 

 acid (Ko SOJ, fused potassium cjanide (KCN), and water, the proportions being one 

 fluid ounce of the acid, one ounce by weight of the dry cyanide, and two fluid ounces of 

 water. The generator is placed under the tent at the base of the tree ; it consists of a 

 common open earthenware vessel. The water is first placed in the generator, then the 

 acid, and last the cyanide, after which the operator withdraws to the outside of the 

 tent and the bottom of the latter is fastened down by having a few shovelfuls of earth 

 thrown upon it. The tent is allowed to remain over the tree for a period of from fifteen 

 to thirty minutes, according to the size of the tree. 



" It was found by experimenting that the trees were less liable to be injured by 

 the gas when treated at night than they were when operated upon in the day-time, and 

 at the same time the gas is just as fatal to the scale insects when applied at night as 

 it would be if applied in the day-time ; and, indeed, it appears to be even more fatal 

 when applied at night. This is accounted for by reason of the fact that in the day- 

 time the light and heat decompose the gas into other gases which, while being more 

 hurtful to the trees, are not so fatal to insects. At night the trees are also more or 

 less in a state of rest, and, therefore, are not so liable to be injured by the gas as they 

 would be in the day-time, when they are actively engaged in absorbing nourishment 

 and replacing wasted tissue with new materials. 



" Of the different materials used in generating the gas, the most important is the 

 potassium cyanide ; of this there are three grades ; the mining cyanide, commercial 

 cyanide, and the C. P. (chemically pure). Of these three brands, the mining cyanide 

 is wholly unsuitable for the production of the gas, and the C. P. is too expensive ; the 

 commercial brand (fused) is the only one that is used for producing the gas, but 

 even this varies greatly in strength, containing all the way from 33 to 58 per cent, 



