444 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 11 
being removed to the air, the stain is again oxidized and the body of 
the insect becomes blue. The following experiments were conducted 
to determine if treatment with an insecticide capable of plugging the 
tracheae would thus reduce methylene blue. 
Exp. 1. Larva? of waxmoth (Galleria mellonella) were injected, with a saturated 
solution of methylene blue by means of a fine glass tube. Some of the larvae were left 
as checks while others were dipped in a light lubricating oil. Larvae not treated with 
the oil remained a beautiful blue w'hile those treated, rapidly faded out, becoming 
white or yellowish white in three to five minutes. Since it was impossible to remove 
the oil from the tracheae, the larvae were then opened with a pair of scissors. The 
tissues and body fluids immediately turned blue on contact with the air. 
Exp. 2. Same as Experiment 1 but when larvae had become white, some of its 
body fluids were carefully removed by a capillary tube. A drop of this blood placed 
on a piece of filter paper or on a glass slide assumed a blue color in a few minutes. 
Exp. 3. Same as Experiment 1 but olive oil used instead of a lubricating oil. 
Results exactly similar were obtained. 
Exp. b Larvae injected with methylene blue and then with olive oil. Although 
the larvae died in a few hours, it remained blue both before and after death. 
Exp. 5. Heavy lubricating oil, so viscous that it was unable to penetrate the 
tracheae, was used to cover over a larva previously injected with methylene blue. 
Larva moved about for four hours, retaining its blue color, after which it was buried 
under a thicker layer of the oil with the result that it lost its blue color and was 
stupified within one hour. The oil was then removed as well as possible, but although 
the larvae again assumed a bluish color, it did not survive the treatment. 
Exp. 6. Injected larvae dipped in toluene and removed; decolorized in six minutes. 
Injected larvae dipped in carbon tetrachloride and removed; decolorized in six min¬ 
utes. Injected larvae dipped in xylene and removed; decolorized in seven minutes. 
Injected larvae dipped in nitrobenzene and removed; decolorized in seven minutes. 
Injected larvae dipped in nicotine and removed; decolorized in six minutes. In¬ 
jected larvae dipped in ether and removed; redipped, decolorized in thirty minutes. 
Exp. 7. Injected larvae placed in small vial with vapor of nicotine. Larvae dead 
in four hours but color had not faded. Larvae kept twelve hours but blue color did 
not fade. 
Exp. 8. Experiment 7 repeated, using nitrobenzene and xylene with similar 
results. 
Exp. 9. Injected larvae placed in water, wdiich did not enter the tracheae. Started 
at 9.15 a. m., decolorized 9.28 a. m. Removed and excess water absorbed with filter 
paper. Larvae again blue in color at 9.32 a. m. Larvae were returned to the water 
at 9.40 a. m. and left until 2.10 p. m. They turned blue at once upon removal to 
the air. 
Exp. 10. Injected larva placed in soap solution 1-500 in such manner that only 
the right spiracles were in contact with the soap. Removed and placed in pure water 
until colorless. Removed from water, dried, and left half of larva assumed a blue 
color while the right side remained colorless. Heart not beating and larva in stupor. 
Placed completely in soap solution and color faded out but did not reappear when 
larva was again dried and exposed to the air. 
Exp. 11. Injected larva placed in soap solution until color had disappeared. 
Removed at 9.40 a. m. and color not having reappeared by 10.02 a. m. it was placed 
in distilled water and thoroughly washed until 10.20 a. m. Removed but color did 
not reappear by 10.37 a. m. 
