THE GREENHOUSE THPJPS. 



57 



Experiment No. 16. — February 20, 1908, sprayed with cold water. 

 Took hose and washed off all of the plants in the greenhouse with cold 

 water. The next morning found the adults still common and also 

 many larvae on the crotons, but many leaves badly infested before 

 washing were then entirely free from them. Probably the spraying 

 with cold water washed away and killed 40 to 50 per cent of young 

 thrips. 



ll'MMARY OF EXPERIMENTS. 



The fumigation and spraying experiments in the control of the 

 greenhouse thrips may be summarized as follows: 



No. of 

 experi- 

 ment. 



Date. 



Method. 



Material. 



Amount per 660 

 cubic feet. 



Per cent 

 killed. 



Injury to 

 plant. 



Status of 

 red spider 

 after treat- 

 ment. 



j 



Apr. 27 

 May 16 

 Apr. 28 

 May 24 

 May 22 

 Apr. 30 



...do 



Mav 1 

 Mav 26 

 Mav 20 

 May 27 

 May 21 



May 18 



May 19 



Feb. 25 



Feb. 20 



Fumigation... 

 do 



Xico-fume paper. 

 do 





92 



56.6 



88 



97 



60.4 



18.8 



11 + 



86.4 



61+ 



100 

 75 



100 



10.9 

 100 

 90 

 40-50 



Xone — 



...do 



...do 



...do 



...do 



...do 



...do 



...do 



...do 



...do 



...do 



...do 



...do 



...do 



...do 



...do 





2 





Do. 



3 



do 



do 



do 



do 



do 



..do 



Aphicide 



do 



do 



Aphis punk 



do 



....do.... 



1 sheet 



Do. 



4 



5 



do 



\ sheet 



Do. 

 Do. 



6 



1 sheet 



Do. 



7 



i sheet 



Do. 



8. 



do 



do 



Do. 



9 



10 



do 



....do 



do 



Nico-fume liquid. 



do 



Rose-leaf insecti- 

 cide. 

 Potassium cya- 



nid. 

 do 



Rose-leaf insecti- 

 cide. 

 Water in hose 



Do. 

 Do. 



11 . 



do 



do 



do 



do 



Spray 





Do. 



12... 



29 c. c 



Do. 



13 



14 



15 



0.00^ gram per 



cubic foot. 

 0.02 gram per 



cubic foot. 

 1 part to 4> parts 



water. 

 Drenching 



Do. 

 Do. 

 Do. 



16 



do 



Do. 



REMEDIES RECOMMENDED. 



For the treatment of this pest there are a number of good remedies. 

 The question as to the best method to employ depends upon the size 

 of the house infested and upon the experience of the person engaged 

 in treating the insect. 



Fumigation with nicotine papers. — Any of the standard fumigating 

 papers will give good results against this pest if they are strictly fresh 

 and kept tightly sealed. Fumigation should be done at night in a 

 moist atmosphere and the papers should be used at the rate (^( about 

 2 sheets for every 1,000 cubic feet oi' space. Early in the morning 

 the house should be opened and thoroughly aired. 



Fumigation with nicotiru liquid extracts. Liquid extracts of nico- 

 tine offer one of the best methods of greenhouse fumigation and against 

 this pest are very successful. Those made up o( 10 per cent nicotine 

 should be used at the rate of 1 ounce to every 1 .000 cubic feet o( space 

 and the weaker solutions at greater strengths. The preparation 

 should be evaporated over small lamps or stoves, and to prevent 



