January, 1916. 



THE CANADIAN HORTICULTURIST 



Insect Pests in the Amateur's Greenhouse 



John Gall, Inglewood, Ont. 



THE combatting of insect pests is 

 always a serious problem to the 

 owner of a greenhouse. Green 

 and black aphids are generally the first 

 insects to make their appearance. They 

 make great headway unless checked 

 when they first appear. A small quan- 

 tity of tobacco stems laid on the 

 benches or, better still, on the hot water 

 pipes, will keep them in check. Replace 

 the stems with fresh ones about every 

 two weeks. 



Nicotine is a splendid insecticide for 

 syringing or spraying almost every- 

 thing in the greenhouse without injur- 

 ing the plants. If diluted to about the 

 color of tea, a teaspoonful to a gallon 

 of water will be strong enough. 



The red spider often becomes a pest 

 during winter months, if the house 

 should become very dry during the 

 night owing to hard firing. It can be 

 killed with nicotine, or, in the case of 

 foliage plants becoming infested, by 

 constant spraying with cold water, 

 especially on the under side of the 

 leaves. 



White and black thrips also can be 

 got rid of by spraying with nicotine. 

 When these pests appear on plants in 

 bloom, the nicotine can be sprayed on 

 the hot pipes after the house has been 

 closed for the night, and the icsults will 

 be surprising. 



The well known mealy bug must be 



watched for and when noticed must be 

 picked off by hand. Spraying mixtures 

 strong enough to kill it will also de- 

 stroy plants. Constant watching and 

 killing on their first appearance, is the 

 best remedy. 



One of the hardest pests to contend 

 with is the white fly. Its presence can 

 be detected by making an examination 

 of the underside of the leaves of the 

 plant. In the adult stage, the insects 

 will fly around the plant when dis- 

 t\u-l)ed, usually returning to the same 

 plant. In lhe egg and nymph stage 

 they are attached to the under side of 

 the leaf, and can scarcely be recognized 

 with the naked eye. This insect has 

 sucking mouth parts and cannot easily 

 be controlled by the use of spray poi- 

 sons. There is but one sure remedy, 

 when once these pests make their ap- 

 pearance in the greenhouse. Prepare 

 to "present arms" to them immediately 

 and keep prepared for their return. 



Hydro-cyanic acid gas is the only 

 kind of fumigation that will clear them 

 out, but on account of its dangerous 

 character on human, as well as insect, 

 life, people are rather timid about using 

 it. If ordinary care is taken, there is 

 not the slightest danger. In using it, 

 the first thing to be done is to measure 

 the cubic feet of the house cai'efully. 

 See that all ventilators are closed, and 

 all doors locked, except the one through 



which you will make your exit. Heat- 

 ing pipes should be set for the night. 

 The temperature of the house should 

 not exceed sixty degrees Fahr. The 

 foliage should be as dry as possible, as 

 the presence of moisture increases the 

 liability of injury to the foliage. Use 

 a stone or glass vessel, and place it in 

 the aisle in the centre of the house. 



The following directions will serve 

 for the use of cyanic acid gas in a small 

 house, about fifteen feet long, eight feet 

 wide, and about seven feet high at the 

 ridge. Put into yoiir vessel a pint of 

 water, then pour in a quarter of a pint 

 of sulphuric acid. Next, place one 

 ounce of cyanide of potassium in a piece 

 of tissue paper, and, when all is ready, 

 drop into the acid. Get out as quickly 

 as possible and lock the door. Allow 

 the gas to remain for about fifteen min- 

 utes, then open the door and allow it 

 to remain open for about hd,lf an hour 

 before any attempt is made to enter 

 the house. By that time all danger will 

 be over. Do not let the acid spatter 

 on the hands, either in handling it, or 

 when placing the cyanide in the vessel, 

 and above all things do not make any 

 attempt to pass the vessel after you 

 have placed the cyanide in it. 



Watch the new house plants, obtain- 

 ed at Christmas time. Hemember they 

 are from a greenhouse, in which the air 

 is moist, so water frequently and thor- 

 oughly. A good way is to set the pot in 

 a tub or pan and sprinkle the leaves. If 

 it is a flowering plant, be careful not to 

 get water on the flowers. 



Fore St. Avenue. St. Thomas, Onl.. i.s liin:d i>\ ihii : ij.siduncu.s u. :.;.:. ,;,;a :i. ;.. !:._ :;.. Tiioiiui.-^ HoiUcultui al Society ha.s planted beds at 

 the corners of the streets similar to the one on the left hand side here shown, which was 4 x 20 feet. The other beds were planted by the 



re.sldents. 



