62 



INS ECTS — LOCUSTS. 



preceding chapter, no insect possesses a true voice. The 

 sounds they make are produced in various ways — for 

 instance, by the wings or the spiracles, by rubbing one 

 part of the body ap;ainst another, etc. 



The power of producing sounds audible to us is pos- 

 sessed by many insects scattered sporadically through 

 all the great groups. 



In many of these cases, the power of producing sound 

 is confined to the males. Their sounds are really love- 

 songs.* 



In Locusts, as Westwood says,t "The stridulating 

 powers of these insects must have attracted the notice 

 of every one who has walked through the fields in the 

 autumn. Unlike tlie insects of the two preceding 

 families, it is owing to the motion 

 of the hind femora, either con- 

 jointly or alternately rubbed 

 against the sides of the wing- 

 covers, that the sound is pro- 

 duced, the insects resting on their 

 four anterior legs during the 

 operation ; the veins of the wing- 

 covers being considerably ele- 

 vated, so as to be easily acted 

 upon by the rugose inner edge of the thigh. Some 

 species, according to Goreau, may be observed to exe- 

 cute this movement without producing any sound per- 

 ceptible to our ears, but which he thinks may be per- 

 ceived by their companions." 



Fig. 44. — Leg of Stevobotkrus 

 pratorum (after Laudois). 



* The females are not, however, invariably dumb. In Ephippigera 

 both sexes are able to produce a sound, which, however, is not very 

 loud. 



t Westwood, "Modern Clussiflcation of Insects." 



