ABSTRACT
In an earlier paper, Eastham & McCully (1943), the results of an investigation into the effects of temperature and humidity on the oviposition responses of Calandra granaria were published. There the effects of environment on the multiplication of cultures of Calandra were recorded in so far as that increase depended upon the rate of egg-laying, number of eggs laid and the length of ovipository life of females. An attempt is made here to extend that information, not only by showing how environment determines the total duration of a developmental period, but how it affects each separate instar of that period from the egg to the emergence of the adult from the pupa.
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Ramsay (1935) gives two expressions for calculating the rate of evaporation of water from a wet surface under two different sets of conditions. It is immaterial in our case which set of conditions is in operation since in our experiments certain of the variables in the expressions function as constants. Provided only that we regard the insect as a water-saturated system which maintains a saturated atmosphere in its immediate vicinity, both of Ramsay’s expressions reduce approximately to the from 
where R = rate of evaporation, T= absolute temperature, s.D. = saturation deficiency of atmosphere to which the insect is subjected. Hence, at a given saturation deficiency, the ratio of the rates of evaporation, R, and R2, at two different temperatures, T, and T2, is given by R1/R2= (T1/T2)2. By arbitrarily fixing one of the temperatures it is thus possible to evaluate a series of ‘temperature factors’ for other temperatures which represent the ratio of the rate of evaporation at the variable temperature to the rate at the fixed temperature. The lowest temperature we employed, viz. 15 ° C. (= 288 ° A.), has been used in our calculations as the fixed temperature and the fraction (T/288)2 evaluated for each of our other experimental temperatures.
