154 
Psyche 
[June- August 
foot-pump duster was directed upward, and at the termination 
of the treatment it was noted that the powder was very uni- 
formly distributed over the ground and lightly over the plant. 
All of the pupse were dead when examined 42 hours after fumi- 
gation. 
In Experiment 55, eight naked pupae and 3 pupae in cocoons 
were treated for 3 hours (3:23 to 6:23 p. m.) on April 5. Only 25 
grams of calcium cyanide was used (2% volume). The tem- 
perature at the beginning of the experiment was 63° F. and 
59 F. at the end; and the relative humidity went up from 
54% to 57%. There was a gentle breeze present, but really 
without effect since the treatment was under the galvanized 
iron can. There was again a uniform distribution of the dust on 
the vine and the ground. When examined on the 7th of April 
all the naked pupse were dead and those in the cocoons were 
stupefied. They never recovered, for on April 10 the three pupse 
in cocoons are recorded as being also dead. 
Another combination of dosage and exposure, under similar 
atmospheric conditions and fatal to the insects treated, was 
found by the test under Experiment 57. Here five cocoons were 
fumigated under the galvanized iron can for two hours with a 
dosage of 2.5% volume (32 grams to the 270 liters of space). 
The temperature rose from 61° F. at the beginning to 64 , and 
the relative humidity dropped from 51% to 47%. When ex- 
amined 48 hours after exposure all five pupse in cocoons ap- 
peared stupefied, while three days later they were pronounced 
dead. 
Perhaps what may be considered the best combination of 
dosage and exposure was that revealed by Experiment 59. On 
April 6 one naked pupa and five in cocoons were treated under 
the galvanized iron can from 4:33 to 6:03 p. m. 38 grams of 
calcium cyanide (3% volume) were used in this experiment. 
The temperature varied from 64° F. to 59° F. and the relative 
humidity was between 47% and 57%. The day was fair, clear 
and calm. Forty hours after the treatment the insects were 
found dead upon examination. 
In all the remaining experiments mortality varied from none 
to 82%. The following chart illustrates the combinations of 
