SUBFAMILY II. OEDIPODIN^. 245 



species with inner wings yellow or hind tibise blue usually occur 

 in an arid or sandy region. 



The members of the subfamily Oedipodina? are peculiar in that 

 the males of most of them and the females of a few stridulate 

 while on the wing, producing a rather harsh, crackling or rattling 

 note by rubbing the under surface of the tegmina against certain 

 veins on the upper surface of the inner wings. The sound seems 

 to be under control of the insect, for they often make it when sud- 

 denly alarmed, or cease making it if too greatly frightened. Some 

 of them produce a uniform rattling note during the entire period 

 of flight, which is generally in a straight course. Others make the 

 call only during certain intervals of flight. These change the di- 

 rection of flight at will, and at every turn emit two or three short, 

 rattling sounds. A number of species also sound a different call 

 when at rest, in the same manner as do the Tryxalinfp, by rubbing 

 the hind femora against the intercalary vein of the tegmina, which 

 is toothed or roughened to aid as a sounding organ. 



In general the Oedipodime, especially those with colored wings, 

 are very shy, alert, and difficult to capture. Owing to their wari- 

 ness they can usually be taken only by first flushing them and 

 then marking down the exact spot on which they alight. Then 

 by approaching carefully one can either throw the net suddenly 

 flat down over them, or, holding it in readiness, can swoop them 

 quickly as they arise. Those with unicolored or faintly clouded 

 inner wings, as the species of C<nitnu1a, Chortophaga, etc., are less 

 wary, usually more abundant in individuals and frequent more 

 open places, so that they are less difficult to capture. In the 

 latitude of Indiana three or four species of Oedipodinre pass the 

 winter as nymphs or half-grown young. These nymphs reach ma- 

 turity about mid-April and are the first Acridians of large size 

 to be seen in the spring. The majority of our species, however, 

 pass the winter, as do most other locusts, in the egg stage. 



Aside from the general works on Orthoptera the literature 

 which will be of especial interest to the student of the Oedipodinse 

 of the eastern States is as follows: Scudder, lS75a, 1875c, 1876, 

 1890, 1892, 1900c; Saussure, 1884, 1888; Morse, 18941), I895a. 1897; 

 McNeil], 1900, 1901 ; RJatchley, 1903; R. & H., 1910. 



The subfamily is represented in our territory by 12 genera, 

 25 species and three races or varieties. All the genera are in- 

 digenous, and their species are confined to North and Central 

 America. For convenience of treatment the genera are grouped 

 into two tribes as follows : 



