14 TETTIGID.E OF NORTH AMERICA 



Moreover, at this later period, in favorable places some species, 

 as Tettigidea and Tettix migrate, and for that reason become 

 abundant locally, for the time being at least. 



MIGRATORY HAUITS. 



One can scarcely conceive of the activity shown in the life 

 of the Tettigida; unless special study has been devoted to them. 

 The warm summer sunlight brings this activity to perfection; 

 the long-winged adult forms delight to sport in the sunshine, 

 instantaneously spreading widely and as quickly closing the 

 prismatic semi-transparent wings. The flight of Tettigids is 

 rapid, noiseless,* and inconspicuous, or some of the abbreviated 

 forms hug the ground closely, scarcely ever attempting flight. 

 Tettigids have amazing leaping power, and their small size and 

 inconspicuous colors and markings have usually made them 

 scarce in collections in which other insects are well repre- 

 sented. A restless period seems to seize some species in the 

 fall of the year, especially among the long-winged forms of the 

 genera Tettigidea and Tettix. At this time local flights have 

 been recorded of considerable extent. In northeastern Illi- 

 nois during sudden storms multitudes are blown into Lake 

 Michigan, from which, however, they usuallyare washed ashore, 

 forming wind rows with the other insects suffering like calam- 

 ity, yet ultimately escape unharmed owing to their naturally 

 semi-aquatic habits. In the American Naturalist, 1894, the 

 writer recorded a flight of these locusts, and since then, on 

 several occasions in the fall, similar migrations have been 

 observed.! With these insects during the flights other larger 

 Acridiida, Lociistidce and Gryllidie are not infrequently associ- 

 ated. 



SEXES UNITING IN THE SPRING. 



The tendency of present-day penetration into the deeper 

 causes of the evolution of sex makes it necessary to record 



* Riley savs of Tettix graimlatus that they tly with a buzzing noise like a Hesh Hy, 

 Rep't U. S. Ent. Conini., p. 256, 1877. 



tProf. J. G. Needham. in an interesting article in "Occasional Memoirs of the Chicago 

 Entomological Society," I, pp. 19-26 (1900). relates a remarkable experience in Hnding multi- 

 tudes among the insect drift along the shore of Lake Michigan. 



