go MANAGEMENT OF THE FORCING-HOUSE. 



Bisulphide of carbon. This material has recently as- 

 sumed a prominent position as an effective insecticide. It 

 is a clear, transparent liquid, which evaporates rapidly, 

 even at a low temperature. These fumes are fatal to in- 

 sect as well as animal life, and may be used to a limited 

 extent in the greenhouse. The vapor is of greatest value 

 in destroying a small mite ( Tetranychus bitnaculatus), 

 that closely resembles the red spider. This mite is not 

 as easily overcome by water as the red spider is, and in 

 certain cases it may be advisable to resort to the bisul- 

 phide of carbon treatment. This treatment is adapted to 

 plants which are growing in pots, or to low-growing 

 plants in beds. Whole houses could scarcely be treated 

 in this manner, as the vapor is heavy, and an uneven dis- 

 tribution would probably result. But for small, con- 

 fined spaces, as bell-jars, tubs, or barrels, the remedy can 

 be used with success. I have had no difficulty in de- 

 stroying mjtes and red spider by the use of 60 minims 

 or drops of the liquid to a space containing about 7 cubic 

 feet. The liquid was poured on cotton batting, which was 

 spread over a small rose from a watering can, the stem 

 of the funnel being set in the soil. The plants remained 

 covered with enamel cloth nearly two hours, which suf- 

 ficed to kill all the insects, and did not injure the violets, 

 these being the plants treated. 



Hydrocyanic gas. The success which has followed the 

 use of hydrocyanic gas in the treatment of scale insects 

 infesting the orange groves of California has suggested 

 the idea of its possible value in destroying greenhouse 

 pests. The common method of making the gas is as fol- 

 lows : One fluidounce of sulphuric acid is slowly added 

 to 3 ounces of water. To this diluted acid there is then 

 added i ounce of 60 per cent cyanide of potassium (very 

 poisonous). Effervescence immediately takes place, and 

 the gas is freely given off. The quantities here given are 

 sufficient for a space containing 150 cubic feet, the plants 

 being exposed to the gas for one hour. When trees are 



