Oct. 16,1916 
Effects of Nicotine as an Insecticide 
101 
indigo-carmine (sodium sulphindigotate) for 45 minutes. These insects 
were fixed in absolute alcohol, which readily throws down indigo-carmine. 
The resulting “precipitate” is totally insoluble in xylol and absolute 
alcohol, but its solubility in the other alcohols increases as the water in 
them increases. Tor this reason the sections of these aphids were stained 
in absolute alcohol containing safranin. The blue “precipitate" was 
common on the outside of the integument, but it was not seen inside the 
integument anywhere, except occasionally in the larger tracheae and then 
usually not far from the spiracles. Plate 1, figure B, represents the 
“precipitate’' ( pr ) observed in two places in the same trachea. This 
drawing was made from two consecutive sections and shows the most 
“precipitate" that could be found. 
The experiment just preceding was repeated by submerging larvae of 
wax moths (Achroia grisella) and small nymphs of croton bugs in the 
above liquid for 30 minutes. A small amount of blue “precipitate" 
(PL 1, fig. C, pr) was observed in most of the larger tracheae of the wax 
moths and occasionally some (PI. 1, fig. D, pr) in the smaller ones. 
Each of the sections of .the croton bugs, containing parts of the ali¬ 
mentary canal, shows more or less blue “precipitate" inside this tube; 
but none was observed elsewhere inside the integument. 
Thirty worker bees were submerged for 30 minutes each in water and 
in pure nicotine solution (1: 500), each liquid being colored with carmine 
acid. When removed from the liquids, the bees were thoroughly washed 
in water. The apparently dead bees were then laid on blotting paper in 
the sun to become dry and to revive from the effects of the liquids. All 
30 bees submerged in the colored water revived and were walking about 
in from 12 to 18 minutes, with an average of 15 minutes, after being placed 
in the sun. Only 60 per cent of those submerged in the colored nicotine 
solution revived, and these never became able to fly as did those sub¬ 
merged in the colored water. The time required for them to recover 
sufficiently so that they could crawl about varied from 45 fninutes to 
3^ hours, with about 2 hours as an average. • 
An examination of the live bees just described showed that the thin 
chitin between the segments was often colored red and that when a 
thorax was crushed, the red liquid usually issued from the mouth. 
When the bees that had been submerged in the colored water were dis¬ 
sected, the stain was seen in 90 per cent of the honey stomachs, in 64 
per cent of the ventriculi, in 50 per cent of the rectums, and in 50 per 
cent of the anal openings and around the stings. When the bees that 
had been submerged in the colored nicotine solution were dissected, 
the stain was observed in 45 per cent of the honey stomachs, in only 
6 per cent of the ventriculi, never in the rectums, and in 45 per cent 
of the anal openings and around the stings. The behavior of the bees 
when placed into the nicotine solution may be used to explain why 
such a small amount of the colored solution passed into the alimentary 
