114 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 3 



species, and that the curve for each species and phase of growth or 

 activity of that species must be plotted before the influence of tem- 

 perature can be exactly stated. It was then stated that we proposed 

 to determine such curves for a number of common insects which could 

 be reared in large numbers at constant temperatures. This we have 

 done and the results are briefly indicated below. The writer fears that 

 his previous paper was possibly too condensed to bring out the prin- 

 ciples suggested and trusts that a ceftain amount of repetition in the 

 present paper may, therefore, be pardoned. 



In the paper cited (24a) the "thermal constant" for insects was 

 defined as "that accumulation of mean daily temperature above the 

 'critical point' of the species, which will cause it to emerge from hiber- 

 nation or to transform from any given stage." 



This idea of a " thermal constant, " or " accumulation of " or " total 

 effective temperature," as expressed by other writers, is a relatively 

 new one in entomological work, although a vast amount of work has 

 been done upon the subject in relation to plant growth by European 

 botanists during the past century. The first attempt to determine 

 such a constant for an insect in America, so far as known to us, was 

 that of Abbe in connection with the hatching of the eggs of the Rocky 

 Mountain Locust (la). No similar study of the relation of accumu- 

 lated temperature seems to have been made until that of Simpson 

 (25) in connection with his Codling Moth investigations in 1903. 

 Simpson gave the "effective temperatures" and the accumulation for 

 different stages of growth, merely stating that "effective tempera- 

 tures" were those over 43 °F. In the following year Hunter and Hinds 

 (12) in their discussion of the relation of temperature to the Boll 

 Weevil use the same method and state, "In considering the influence 

 of temperature upon the weevils it has been assumed that, as has been 

 found to be the case with other animals, 43 °F. would be about the 

 lowest temperature at which the weevils would be active . . . For 

 this reason it is better to speak of the 'effective temperature,' meaning 

 by that the number of degrees above 43°F." The next year Quain- 

 tance and Brues (19x) in their discussion of the relation of tem- 

 perature to the Cotton Bollworm use the same method, but definitely 

 attribute the origin of the idea to the paper of Merriam (17), and 

 show that 45° gave rather a more constant sum of effective tempera- 

 tures than when 43°F. was used as a basis. In 1904 the writer (24) 

 endeavored to show a method whereby the emergence of the boll 

 weevil from hibernation could be determined by the accumulation of 

 temperature and in 1906 Newell and Martin (19) made practical 

 use of the data of Hunter and Hinds in determining the time of migra- 



