368 GOUREAU ON THE 



Although the sounds now under consideration are essentially 

 different from those of Orthoptera, I shall continue to give 

 them the name of Stridulation, in order to include in one term 

 the voices of all insects. 



Coleoptera. — There are a great many Coleoptera which 

 possess the power of producing sounds. Amongst these we 

 may mention, in the first place, the numerous family of Ceram- 

 hycidcF. The noise is made by rubbing the praescutum of the 

 mesothorax against the inner border of the prothorax. This 

 praescutum is smooth in some species— in Ccramhyx keros, for 

 instance. In others it has a longitudinal and slightly elevated 

 smooth band in the middle, as in Lamia textor ; it is this 

 smooth part which rubs against the border of the prothorax, 

 and produces the sonorous vibration. In Crioceris or Lema, 

 stridulation is produced in the same way. Other Coleoptera 

 have their sonorous organ placed at the extremity of the abdo- 

 men ; Copris, Geotrupes, Cychrus and Fcdciger echii are instances. 

 When these insects draw up the extremity of the abdomen 

 under the wing-cases, the tergum of the last segment, and the 

 lateral borders of the preceding ones, rub against the edge of 

 the elytra, and produce stridulation. The Necrophori carry 

 their sonorous organ upon the tergum of the fourth abdominal 

 segment; it is composed of two parallel smooth and elevated 

 lines, which appear to be a prolongation of the suture of the 

 elytra. When insects of this genus draw their abdomen under 

 the wing-cases, these two lines rub against the posterior border, 

 and produce a very distinct sound. In all the before-named 

 insects, stridulation may be artificially pi'oduced by moving 

 the head up and down, or forcing the abdomen under the 

 elytra. Besides these, Hygrobia and Pimelia are said to possess 

 the power of producing sounds, but as I have not heard theai, 

 I am not able to say where their sonorous organs are situated. 



Hemiptera. — Among Hemiptera I only know one genus, 

 Reduvius, the species of which emit a slight sound. When 

 these insects are confined or disturbed, they may be seen to 

 move their heads, alternately laising and depressing them with 

 rapidity ; at the same time, a faint monotonous kind of stridu- 

 lation is heard. It is produced by the friction of the neck 

 which is formed of a smooth, shining, scaly ring, against the 

 anterior border of the prothorax. 



Hymenoptera. — The order Hymenoptera furnishes one 



