FAMILY V.-GKOUSE LOCUSTS. 105 



fProsternum with a prominent spine Acridinae. 



2 < Prosternum not spined, or with only an oblique tuber- 



I cle 3 



/Face Yer_v oblique Tryxalinae. 



[Face not oblique, or but siightl}^ so Q^ dip o dings. 



SUB-FAMILY TETTIGIN.^. 



GROUSE LOCUSTS. 



These very small locusts possess a very unusual form, 

 having the pronotum prolonged to such an extent that it 

 projects to or beyond the abdomen. The head is deeply set 

 in the pronotum, and the prosternum is expanded into a 

 broad border parti all \^ enveloping the mouth. The short 

 antennae are ver}* slender. The wing-covers are rudimentary, 

 and resemble small rough scales ; the wings are very large 

 in proportion. Members of this sub-family possess no pul- 

 villi between the claws of their tarsi. 



TettiginjE are very common in some localities, and espe- 

 cially near the shores of our lakes. Here they feed upon 

 such lowly organized plants as lichens, molds, etc., in fact 

 they eat mud containing decayed vegetable matter, and in 

 this way they act verj^ differently from other members of 

 the order of orthoptera. Being usually of a dark 

 color, which blends with the soil upon which the insects rest, 

 they can not readily be seen ; nor are they easily captured, as 

 they are very active and possess enormous leaping powers. 



There are t"wo groups of Tettiginee : 

 A. Anterior femora more or less compressed, carinate above; 



antennae with 1 2-14- joints Tettigias. 



AA. Anterior femora distinctly and broadly sulcate above; 

 antenna with 15-22 joints Batrachidese. 



We possess three genera of Tettigiae in Minnesota: 

 A. Median carina of pronotum cristiform; superior lateral 

 sinus (at insertion of tegraina) shallow, not nearly 



so deep as the inferior sinus Nomotettix. 



AA. Median carina of pronotum low; superior lateral 

 sinus nearly as deep as the inferior sinus. 



