188 



FAMILY VI. ACRIDIDJE. THE LOCUSTS. 



Fig. 67. Inside of 

 hind femora of a locust; 

 s. ridge with teeth. 



years invade our fields and forests in such countless numbers. 

 The name "jumping grasshoppers" is also sometimes given our 

 Acrididse to distinguish them from the "green" or "long-horned" 

 grasshoppers belonging to the genera Orchelimum and Conoceph- 

 alus of the family Tettigouiidre. Latreille (1831, 15), in compar- 

 ing the Acrididse with the other families of Saltatoria says of the 

 former: "They leap better, fly higher and longer, and feed vo- 

 raciously on vegetables." 



The call notes made by the males of the Acrididse are pro- 

 duced in two ways and in the daytime only. One group, whose 



members call only when at rest, stridulate by 

 rubbing the inner surface of the hind femur 

 against the lower outer edge of the tegmina. 

 Landois has shown that in this group the in- 

 ner surface of the femur is furnished along 

 the lower margin with a longitudinal row of 

 minute, lancet-shaped, elastic teeth, ranging 

 i ]1 "umber from 85 to 03, which are scraped 

 ^^oss the edge of the tegmina, thus causing 

 them to vibrate and produce a low, buzzing 

 sound (Figs. <>7, (8). Those Acrididse which stridulate in this 

 manner are mostly members of the subfamilies Tryxalinse and Lo- 

 custinse. Allard (1916) says that "at best their stimulations are 

 hardly more than a brief lisping or a 

 noisy crepitation," and states that 

 the notes of two of the Tryxalinse, 

 Chortliippiis cnrti pen nis (Harr.) and 

 Eritciti.r simplex (Scudd.) are pro- 

 duced by "sawing both thighs simul- 

 taneously upon the edges of the teg- 

 mina." In the genus Jlecostcthns 



the teeth are borne on the intercalary vein of the tegmina and 

 some of its branches, the ridge of the femur being smooth. 



The members of the subfamily Oedipodhw usually sound their 

 call during flight by rubbing together the upper surface of the 

 front edge of the wings and the under surface of the tegmina, thus 

 producing a sharp, crackling sound which has been likened to that 

 of burning stubble. However, some of the Oedipodinse stridulate 

 at rest as well as during flight. Thus says Scudder (1803, G3) 

 "Acridians shuffle, rustle and crackle, while crickets shrill and 

 creak and Locustarians scratch and scrape." By paying close at- 

 tention, the observer can soon learn to know each species by its 





Fig. 68. Ridge and teeth of 

 hind femur greatly enlarged. (After 

 Landois.) 



