THE GREENHOUSE THRIPS. 



57 



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

 Took hose and washed off all of the plants in the f^reenhoiise with cold 

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

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

 washing were then entirely free from them. Probably the spra3'ing 

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

 thrips. 



SUMMARY OF EXPERIMENTS. 



The fumigation and spraying experiments in the control of the 

 greenliouse thrips may be summarized as follows: 



REMEDIES RECOMMENDED. 



For the treatment of this j)est 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. — An}' 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 of about 

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

 the house should be opened and thoroughly aired. 



Fumigation with nicotine 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 of 40 per cent nicotine 

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

 and the weaker solutions at greater strengths. The preparation 

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



