NICOTINE SULPHATE AS AN OVICIDE AND LARVICIDE. 3 



soap, 2 pounds to 100 gallons of water) ; some with nicotine sulphate 

 1:800; some with nicotine sulphate 1:1,066; and others were not 

 sprayed, these being used as controls. During October, 1916, all of 

 the eggs 14 months old hatched, but the hatching of the sprayed ones 

 was more or less retarded. Relative to the eggs from 1 to 6 days old 

 when treated, the following data were obtained during the spring of 

 1917. Only 1 per cent of those sprayed with nicotine sulphate 

 1 : 800 hatched, while 80 per cent of the unsprayed ones hatched ; in 

 regard to the eggs 3 months old, 20 per cent of those sprayed with 

 nicotine sulphate 1 : 800-fsoap hatched, 25 per cent of those sprayed 

 with nicotine sulphate 1 : 800 hatched ; 35 per cent' of those sprayed 

 with nicotine sulphate 1 : 1,066 hatched ; while 90 per cent of those 

 unsprayed hatched. The unsprayed eggs hatched quickly, and the 

 newly hatched larvse grew normally, while the sprayed eggs were 

 more or less retarded in hatching and the young larvae were so 

 stunted that after 20 days the larvae from the unsprayed eggs were 

 from 1 to 6 times as large as those from the sprayed eggs.' A large 

 percentage of the unhatched eggs contained embryos aborted during 

 the last stage of development. 



EFFECTS OF NICOTINE ON NEWLY HATCHED SILKWORMS. 



Mclndoo (6, p. 97) has already shown that the exhalation (called 

 odor) from leaves an hour after having been sprayed with a solution 

 of nicotine sulphate kills small fall webworms (Hyphantria cunea 

 Dru.), small caterpillars of the catalpa sphinx (Ceratomia catalpae 

 Bdv.), and certain aphids (Aphis populifoliae Davis). 



On May 12 at 12.30 p. m. a bunch of leaves on a mulberry tree was 

 dipped into a solution of nicotine sulphate 1 : 400 and another bunch 

 into a solution 1 : 800. On May 14 at 9.30 a. m. a leaf was removed 

 from each bunch of the leaves treated, and 20 silkworms 1 day old 

 were placed on each leaf; at 12.30 p. m. all the worms were dead. 

 The leaves still emitted a faint odor like that from the solution. 

 On May 16 at 11.15 a. m. the preceding experiment was repeated; 

 on May IT at 9 a. m. 8 worms on the leaf treated with the solution 

 1 : 400 and 1 on the other leaf were dead ; all of the remaining live 

 worms were more or less stupid, and two hours later, after having 

 been fed with a fresh leaf treated with the solution 1 : 400, died. 

 This leaf was cut into small pieces, and it still emitted a very faint 

 odor like that from the solution, but the leaves treated with the 

 solution 1 : 800 had ceased to emit this odor so far as the observer 

 could perceive. At no time during any of the preceding experiments 

 did the silkworms eat the treated leaves ; the exhalation arising from 

 them therefore must have killed the worms. 



