OKTHOPTEKA OF INDIANA. 211 



Family ACRIDID^. 



To this family of saltatorial Orthoptera belong those short-horned 

 grasshoppers or locusts which are so common in our meadows and 

 pastures and along our roadsides from mid- April until after the heavy 

 frosts of late autumn. Their antennae are, Avith few exceptions, much 

 shorter than the body, filiform, clubbed or ensiform in shape, the 

 joints distinct, and often, especially toward the base, depressed. The 

 head is usually short, and in the leading sub-families is extended 

 horizontally. Ocelli are always present, and foveola usually so, the 

 variations in form and size of the latter affording characters much 

 used in classification. 



The pronotum is variable in form and size, but in most species 

 forms a buckler or saddle-shaped shield covering the three segments 

 of the thorax. In one sub-family, the Tettiginw, it extends back over 

 the abdomen. The tegmina and wings, when present and in repose, 

 rest partly horizontal on the dorsal surface of the abdomen and partly 

 reflexed against its sides. The auditory or hearing organ, when pres- 

 ent, is located on the side of the basal ring of the abdomen. The an- 

 terior and middle legs are equal or nearly so in size, and much smaller 

 and shorter than the hind legs; the femora of the latter being, as in 

 the other Saltatoria, very much enlarged in their basal halves. The 

 tarsi are three-jointed and similar in structure on all the legs; the 

 first joint, usually the longest, has the under side marked with two 

 cross impressions which, when seen from below, give the impression 

 that it is composed of three segments. The third or apical segment 

 of the tarsus ends in a pair of curved claws which enable the insect 

 to catch and cling to blades of grass and other objects on which it 

 may alight. BetAveen these claws there is in the species of all the 

 sub-families except those of the Tettigince a circular pad or cushion, 

 Called the pulvillus or arolium. The ovipositor consists of four short, 

 horny pieces, the so-called valves, projecting from the tip of the ab- 

 domen, tAvo of Avhich curve upward and two doAvnward. 



The call notes made by the males of the Acrididce are produced in 

 two Avays. In one group, Avhose members call only when at rest, the 

 sound is produced by rubbing the inner surface of the hind femur 

 against the outer surface of the tegmina. Landois has shoAvn that 

 in this group, the inner surface of the femur is furnished along the 

 lower margin Avith a longitudinal row of minute, lancet-shaped, elastic 

 teeth, ranging in number from 85 to 93, which are scraped across the 

 veins of the tegmina, thus producing a Ioav, buzzing sound. Those 



