80 THE EEPOKT OF THE No. 36 



shelter in green houses or homes where plants are kept and a constant reproduc- 

 tion is kept up the year round. 



Another way in which these species do injury is due to the supply of honey 

 dew given off where a fungus grows and spreads over the surface of the leaf, inter- 

 fering with the nutrition of the plant. 



The insect is not a good flyer, but can go considerable distances with the wind, 

 and whole neighborhoods are often infected in this way. The flies are often car- 

 ried from place to place on infested plants or parts of plants for identification 

 purposes. They cling tenaciously to clothing and are sometimes carried from 

 greenhouse to garden in this way. 



So far very few parasites have been found at work on the Aleyrodidse of this 

 country and these have not yet been identified. In South America and other 

 tropical countries many species have been found, notably the families Tricho- 

 grammatidse, Aphelinidae, Eupelinidae, Mymaridse, Platygastridop, Diapridse, For- 

 micoidaB of the Hymenoptera, Chrysopa of the Neuroptera, Thrips, belonging to the 

 Thysanoptera ; Mites of the Acarina. In addition to the above-mentioned families 

 of insects and acarids two genera of fungi, Aschersonia and Sphaerostilbe also 

 assist in the control of the White Fly. 



It is my experience that considering all kinds and conditions of plants and 

 greenhouses cyanide of potassium, although perhaps^used the least, is the cheapest 

 and most effective means for fumigation. The best results are obtained by using 

 % of an ounce of potassium cyanide at a cost of 2^ cents, and lyi ounces of sul- 

 phuric acid at a cost of about 14 cent, per thousand cubic feet. This method, 

 besides costing only about 2^^ cents per thousand feet, is thoroughly effective and 

 requires little labor in its application. 



As this means has heretofore been considered by a great many florists as 

 dangerous to human life in its application, it has been but sparsely used. The solu- 

 tion, however; is so weak that there is not the least danger to human life or health 

 if only the simplest precautions are taken. 



The formula recommended is as follows : 

 Potassium cyanide, 1 ounce by weight; 

 Sulphuric acid, 1^^ ounces by volume; 

 Water, 3 ounces by volume. 



The cyanide should in all cases be chemically pure, 98 per cent pure cyanide, 

 and the sulphuric acid should be the best commercial, or 85 per cent, grade. It 

 is always best to have the cyanide broken up into small pieces. Generators should 

 always be earthen or glass vessels, never metal, having a gallon capacity. In order 

 to distribute the gas equally throughout the greenhouse it is well to place the 

 generators at equal distances apart along the walls. The greenhouse should be as 

 much as possible airtight, with dry atmosphere and a temperature of below 60 

 degrees Fahrenheit, and the generation of gas should be done after darkness has set 

 in. After having placed the generators properly, with water and sulphuric acid, 

 the packages of cyanide are then added, commencing at the generator farthest from 

 the place of exit, and the operators should then leave as soon as possible and close 

 the door. The dropping of the packages of cyanide into the generators by means of 

 a cord operated from a position outside of the greenhouse is entirely unnecessary 

 and is now quite obsolete, as the fumes from the composition are too weak to do any 

 injury. The quantity of the doses must, however, always be regulated by the florist 

 from the condition of the greenhouse, the plants, and the insects to be destroyed. 



It is the confidence I have in the remedy which prompts me to highly recom- 

 mend it as the cheapest and most effective means for destroying the White Fly in 



