46 



fied and apparently killed, but all recovered in the course of 12 

 hours. 



10. Rate : .01 gm. KCN per cu. ft. of space. Time of expo- 

 sure, 15 minutes, cloudy afternoon. Plants treated: Cucumber 

 and tomato. Results: Plants uninjured; about 50 per cent of 

 adults were dead when box was opened, but the remainder showed 

 signs of life, and some of these finally fully recovered. 



1 1. Rate : .005 gm. KCN per cu. ft. of space. Time of expo- 

 sure, 30 minutes, after sunset. Plants treated : Cucumber and to- 

 mato, and a sprig of Eupatorium infested with plant lice. Results : 

 Plants uninjured ; all adult Aleyrodes killed, though many showed 

 slight signs of life for a few honrs. Plant lice stupified, but recov- 

 ered within twelve hours. 



12. Rate : .005 gm. KCN per cu. ft. of space. Time of expo- 

 sure, after sunset, 6 to 9 p. m. Plants treated: Tomato and cu- 

 cumber, the latter badly infested with red spider. Results : Plants 

 uninjured; all adults killed, a few showing signs of life for a few 

 hours ; two-thirds of larvae and pupae killed ; eggs unaffected. 



13. Rate : .007 gm. KCN percu. ft.-of space in a loose green- 

 house containing 1700 cu. ft. of space. Time of exposure, after 

 sunset, 6.45 to 9.45 p. M. Plants : Tomatoes, with many of leaves 

 nearly dead from results of insects' attack, and cucumber infested 

 with red spider. Results : Plants uninjured ; all adult Aleyrodes 

 killed ; 90 per cent of larvae and young pupae killed, and 2 or 3 per 

 cent of old, nearly mature pupae killed ; eggs unaffected ; red spider 

 unaffected. 



14. Rate ; .01 gm. KCN per cu. ft. of space in same green- 

 house used in last experiment. Time of exposure, after sunset, 6.45 

 to 9.45 p. m. Results : Plant uninjured ; all of adults, all larvae 

 and young pupae and about 75 per cent of old, nearly mature pupae 

 killed ; eggs apparently unaffected. 



15. Rate: .02 gm. KCN per cu. ft. of space (in fumigating 

 box). Time of exposure, after sunset, 7.30 to 10.30 p. m. Plants : 

 Tomato and cucumber, the former being small plants, showing the 

 effects of improper nutrition, the latter being badly infested with red 

 spider. Results : The smaller and less vigorous of the two tomato 

 plants used showed slight injury to some of the tenderest leaves ; the 



