October, ’24] 
SHEPHERD: BIOLOGY OF ECHOCERUS CORNUTUS 
577 
tions of calcium chloride giving the atmosphere a humidity of approxi¬ 
mately 25%; copper nitrate approximately 45%, sodium chloride 75% 
and thru distilled water approximately 100%. Atmosphere of room 
humidity was introduced into one of the bell jars and atmosphere drawn 
thru a calcium chloride dryer was introduced directly into another bell 
jar. The atmosphere was taken from the bell jar having the selected 
percentum of atmospheric moisture to a constantly functioning suck 
pump. 
Using the following as an index as to the effect of the different .per¬ 
centages of moisture; the number of beetles surviving; the number of 
living and dead larvae; the increase in the number of larvae in first in¬ 
stars, I reached the following conclusions: extending over a period of 
fifty days in a mean temperature of 65°F. adult beetles and larvae in the 
last instars seem to be but slightly affected by an atmospheric humidity 
ranging from approximately 1% to 100%. As the humidity increases up 
to 75% the number of dead beetles in the jars increase; from the fact 
that I found as many dead beetles in the jar having 100% as in the jar 
having 45% this data does not seem to be conclusive and further ex¬ 
perimentation is necessary to test out this discrepancy. A very marked 
increase in the number of larvae of the first instars accompanies an in¬ 
crease in humidity, the actual numbers in increase being from 58 in at¬ 
mosphere of 1% humidity to 412 in a humidity of approximately 100%. 
The optimum humidity for young larvae of Eckocerus cornutus is 
approximately 100% but with this humidity, in the course of thirty 
days, a fungus appears which no doubt would, in a very short time be 
destructive to all beetles. In the light of this then it is quite possible 
that the most favorable condition for the development of this beetle 
would be in an atmosphere of a humidity of somewhere between 75% 
and 85%. In this experiment no account was taken of changes of tem¬ 
perature and light as I considered that for practical purposes perfect 
control of these factors was unnecessary. 
It is unfortunate that the test could not be extended over a longer 
period of time,—I intend, however, at a very early date, to repeat this 
test, extending it over a much longer period of time. 
Methods of Control. The chief means of control of Eckocerus 
cornutus are the use, in Germany, of Bacillus-thuringensis ; in England, 
hermetical sealing; in Canada, of chloropicrin, and in the United States 
and elsewhere, the elimination of breeding places, fumigation with car¬ 
bon bisulphide and hydrocyanic acid gas and the heating of mills to a 
temperature of 120°-130°F. for a period of twelve hours. 
