22 



treated insects with normal ones, and immediately after death, to fix 

 treated individuals in a fluid containing a nicotine precipitant. 



Nicotine as a stomach poison was tested on bees, which were fed 

 on 10 cc. of a mixture of nicotine with honey (1 : 100). Death 

 ensued in 33 hours on an average, whereas bees fed on pure honey lived 

 on an average for eight days. The effect of the poison w^as to cause 

 paralysis. 



The next experiments deal with nicotine in spray solutions. Wh' -i 

 leaves of Carohna poplar [Populus deUoides) bearing Aphis popuUfoliae, 

 Davis, were dipped in a solution of pure nicotine (1 : 100), all the 

 Aphids were dead in half an hour. On leaves sprayed with the same 

 solution, nearly all the Aphids died in from 30-45 minutes. When 

 leaves bearing Aphids were sprayed with a solution of nicotine sulphate 

 (1 : 64), they all died within four hours. With the same solution, the 

 large caterpillars of the catalpa sphinx {Ceratmnia cakilpae, Bdv.) died 

 in an hour and smaller ones sprayed with a much weaker solution 

 (1 : 1,200) died in 5 minutes. An extract of 50 gms. of tobacco boiled 

 in 1,000 cc, of water gave a similar result. Small caterpillars of 

 Atteva aurea, Fitch, and of Daiana sp. were quickly killed by the 

 stronger nicotine sulphate solution, but the larger larvae of the lesser 

 wax moth {Achroia grisella, F.) and of the bag- worm, Thyridopteryx 

 ephemeraeformis, Haw., showed greater resistance. Three out of four 

 adult blister beetles {Epicauta pennsylvanica, DeG.) thus sprayed, also 

 died, but worker bees could not be killed by spraying. 



For testing nicotine as a fumigant, a special apparatus was used. 

 A piece of rubber tubing 12 inches in length with its free end projecting 

 into a battery jar 9 inches in diameter and 12 inches high was con- 

 nected to the neck of a 55 cc. retort supported on a ring stand. The 

 jar was covered with a piece of glass. Twenty-five cc. of pure nicotine 

 placed in the retort was heated, and when the whole apparatus was 

 sufficiently warm to prevent recondensation, the free end of the tubing 

 was inserted into the battery jar containing the specimens to be 

 experimented upon. On removing the burner, the nicotine con- 

 densed as a fine spray on the leaves, insects and sides of the jar. In 

 the case of Carolina poplar leaves bearing Aphis populifoliae and 

 nasturtium leaves bearing Aphis rumicis, L., all the Aphids were dead 

 within five minutes. When a 40 per cent, solution of nicotine sulphate 

 was substituted, the Aphids on nasturtiums, as well as Myzns persicae, 

 Sulz., on potatoes, and the scale, Orthezia insignis, Dougl., died within 

 a few minutes, though the plants were also considerably affected ; 

 caterpillars of the fall webworm [Hyphantria cunea, Dru.) and larvae 

 of potato beetles {Leptinotarsa decemlineata, Say) died only after being 

 confined in dense fumes from 15 to 20 minutes. Worker honey bees 

 die in the same length of time, but the adults of Mu^ca domestica, L., do 

 not die so readily. Bees apparently dead may recover when 

 removed to fresh air. 



Several other experiments with nicotine odour and vapour were 

 made, the same forms of nicotine being used. Aphis populifoliae 

 placed on Carohna poplar leaves previously dipped in pure nicotine 

 solution and thoroughly dried, were dead within 24 hours, though none 

 of the Aphids used as controls died. Examples of Aphis brassicae 

 placed on wire screens over watch-glasses containing pure nicotine 

 solution (1 : 100), died in from 10 to 22 minutes. Extensive experi- 



