20 



BULLETIN 833, U. S. DEPARTMENT OF AGRICULTURE. 



EXPERIMENT 3. 



In the foregoing experiment it will be observed that good results were 

 obtained with the nicotine sulphate diluted to 1-800. Another point 

 upon which it seemed desirable to have more definite information 

 was the effectiveness of applications made daily compared with 

 those made two days apart. In the following experiment two lots 

 were treated, while the third lot served as a check. The empty galls 

 were punctured and all old pupal skins were removed from the 

 plants in question. Eighteen plants were employed in each of the 

 two treated lots, which were sprayed a total of five times. Five 

 plants served as a check. 



Table VII. — Results on first and second days after treatment. 



Lot. 



Treatment. 



Results first day after 

 treatment. 



Results second day after 

 treatment. 



Males. 



Fe- 

 males. 



Total 

 killed. 



Pupal 

 skins. 



Males. 



Fe- 

 males. 



Total 

 killed. 



Pupal 

 skins. 



1 

 2 



Nicotine sulpnate 40 per cent (1-800) 



and soap 



Volatile nicotine sulphate 40 per cent 



3S 



18 







43 



18 

 2 



SI 



36 

 2 



15 



22 



74 



1 

 1 



1 

 2 



2 

 3 



16 

 23 



3 

















Conclusions. — The results are very conclusive and show distinctly 

 that the best results are obtained by daily application. There is a 

 remarkable decrease in the numbers caught on the second day fol- 

 lowing treatment. Nicotine sulphate, therefore, used at the rate of 

 1-800 plus soap (1 ounce to 1 gallon) will control the adult on emer- 

 gence, and hence is very well adapted to such cases where fumigation 

 can not be followed consistently. 



EXPERIMENTAL WORK IN COMMERCIAL CHRYSANTHEMUM GREENHOUSES. 



Experimental work in a commercial greenhouse in Baltimore 

 during the summer of 1918 seems to indicate that the chrysanthemum 

 midge can be held well under control by spraying the infested plants 

 with 40 per cent" nicotine sulphate applied at the rate of 1 part of 

 nicotine sulphate to 500 parts of water, with the addition of one- 

 half ounce of soap to each gallon of solution. No appreciable injury 

 followed the application, although the plants were sprayed every 

 other day for a period of six weeks. The application of this treat- 

 ment by the grower resulted in his producing especially fine chrys- 

 anthemums. It would appear that a double benefit was realized 

 by such practices. In the first place it controlled the insect, and, 

 secondly, a distinct stimulation of growth followed. This seems to 

 confirm the work of Gossard (30) and Guyton (31), who claim that 

 40 per cent nicotine sulphate diluted with 500 parts of water and 



