ENTOMOLOGY 



gare, may be represented by a prolonged zr . . . sound, followed by 

 a staccato jip-jip-jip-jip. . . . 



In Orthoptera, the frequency of stridulation increases with the tem- 

 perature; and the correlation between the two is so close that it is easy to 



B 



FIG. 136. Stridulating organs of Microcenlrum laurifolium. A, dorsal aspect of file (st) 

 when the tegmina are closed; B, ventral aspect of left tegmen to show file; C, dorsal aspect 

 of right tegmen to show scraper (s). 



compute the temperature from the number of calls per minute, by means 

 of formulae. The formula for a common cricket [probably a tree-cricket, 

 (Ecanthus niveus], as given by Professor Dolbear, is 



T= 50 + 1 4 > which simplified is ^ = 40 + ^ . 



Here T stands for temperature and ^V, the rate per minute. 



A similar formula for the katydid (Cyrtophyllus perspicillatus), based 

 upon observations made by R. Hay ward, "would be 



Here, in computing A T , either the "katy-did" or the "she-did" is taken 

 as a single call. 



