8 4 



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 



s 'l\pw 



B 



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

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

 of right legmen 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 



A 7 40 i i ive j T N 



T= 50 + ~, which simplified is 1 =40 + -. 



Here T stands for temperature and A r , the rate per minute. 



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

 upon observations made by R. Hayward, would be 



N-ig 



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

 as a single call. 



