56 



MISCELLANEOUS RESULTS OF WORK OF BUREAU IX. 



Experiment No. 13. — May 18, fumigated with potassium cyanid 

 (O.OOf gram per cubic foot. In 660 cubic feet used 4.4 grams ])otas- 

 sium cyanid, 7.92 c. c. sulphuric acid, and 15 c. c. water). Time, 5.30 

 p. m. Sky clouded; temperature S2° F; breeze strong; length of 

 fumigation, overnight. 



May 19, the plant was uninjured. 



This strength was entirely too weak. 



Experiment No. IJ,. — May 19 fumigated with potassium cyanid 

 (0.02 gram per cubic foot. In room used 13.2 grams potassium cya- 

 nid, 26.8 c. c. sulphuric acid, and 53.6 c. c. water). Time, 6 p. m. 

 Length of fumigation, all night. Temperature, 78° F.; breeze strong. 



May 20, the plants were uninjured. Flies and bees in the room 

 were all dead. Red spiders were alive. The thrips were all dead. 



May 25, the plant was uninjured. 



SPRAYING EXPERIMENTS. 



Experiment No. 15. — February 25, sprayed very thoroughly with 

 rose-leaf insecticide (1 part to 48 parts water) a large croton infested 

 with this thrips in all stages. Gave the upper and under sides a very 

 thorough spraying so as to cover entirely the surface and be sure to hit 

 nearly all of the thrips. The spraying was done in the afternoon 

 when the house became shaded from the sun. A fine spray from a 

 small hand pump, common in greenhouses, was used. 



February 26, examined the plant at 9.30 a. m. and find results as 

 follows : 



May 12, 1908, this plant had then a number of young thrips upon it 

 again and a lot of adults that bad flown onto it. 



