THE GREENHOUSE THRIPS. 



57 



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

 Took hose and washed oil" all of the plants in the greenhouse w^ith cold 

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

 many larva^ 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. 



SUMMARY OF EXPERIMENTS. 



The fumigation and spraymg experiments in the control of the 

 greenhouse thrips may be summarized as follows: 



experi- 

 ment. 



Date. 



1 Apr. 



2 Mav 16 



3 Apr. 28 



4 Mav 24 



May 22 



Apr. 30 



...do 



Mav 1 



Mav 2(j 



10 Mav 20 



11 Mav 27 



12 May 21 



13. 



Method. 



Material. 



Amount per 660 

 cubic feet. 



Fumigation...: Nico-fume paper. 1 sheet. 



do do I J sheet. 



do -Vphicide i 1 sheet. 



do do do.. 



do do J sheet. 



do .Vphis punk [ 1 sheet. 



do do ! 4 sheet - 



do } do j do.. 



do do do.. 



do Nico-fume liquid.' .Jounce. 



.do. 

 .do. 



.do. 

 .do. 



Spray. 



.do. 



Rose-leaf insecti- 

 cide. 



Potassium cya- 

 nid. 



i ounce. 

 29 c. c. 



QMS gram per 

 cubic foot. 



do 0.02 gram per 



cubic foot. 

 Rose-leaf insecti- ; 1 part to 48 parts 



cide. ' water. 

 Water in hose Drenching 



i Status of 



Per cent ' Injury to red spider 

 killed. plant. after treat- 

 ment. ■ 



92 None Vlive. 



50. () ...do Do. 



88 ...do Do. 



97 ...do Do. 



(iO.4 ...do Do. 



18.8 ...do Do. 



in- ...do.....l Do. 



86.4 ...do Do. 



61-1- ...do Do. 



100 ...do Do. 



75 ...do Do. 



100 ...do Do. 



10.9 ...do Do. 



100 ...do Do. 



90 ...do Do. 



40-50 ...do Do. 



REMEDIES RECOMMENDED. 



For the treatment of this pest there are a number of good I'emecUes. 

 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 witli nicotine papers.— Any of the standard fumigating 

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

 and kei't 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 thoioughly aired. 



Fumigation with nicotine liquid extracts. — Liquid extracts of nico- 

 t ine 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 greatei' strengths. The preparation 

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



