IOWA ACADEMY OF SCIENCES. 175 



as distinct species, and also to separate as distinct seme forms 

 hitherto included with other known species. 



Color ational characters in certain genera are of very little 

 value, since it is found that summer broods and species occur- 

 ring in shaded localities are pallid or unicolorous, while autumn 

 broods or exposed individuals assume darker and more definite 

 markings, often varying to black. 



Another feature of considerable interest and of value in the 

 discrimination of species is presented in the fact that for a 

 number of species there are distinct long and short winged 

 forms with consequent variations in venation (usually given 

 generic importance) the long winged condition apparently asso- 

 ciated with a migrant habit. 



The grasses which have been more particularly under obser- 

 vation during the season and which seem to have each its par- 

 ticular jassid fauna, are: Blue grass {Poa pratensis), Andro- 

 pogon scoparms and provincialis, Elymus canadensis and virginicus, 

 Bouteloa hirsuta and cutipendula, Stipa spartea, Spartina cynosuro- 

 ides, Sporobolus hookeri, heterolepis, asper and cryptandrus, Chry- 

 sopogon nutans, Mulileiibergia 7'acemosa, diffusa and sylvatica, 

 Bromus cUiatus and purgans; also a number of annuals, espe- 

 cially the Panicums and Setarias. 



A statement of the known host plants accompanies the dis- 

 cussion of each species. 



TETTIGONIA BIFIDA SAY. 

 Journal Acad. Nat. Scf., Pliila., IV, p. 313, 1831; Comp. Writings II, p. 387, 1869. 



This is a rather handsome little species, and its range of food 

 habit seems to be more restricted than many of the others, it being 

 found only on blue grass in shady places. The latter restric- 

 tion confines it to wooded pastures, where it is perhaps almost 

 as common though less universal than inimicus in open pastures. 



The adult is about six millimeters long, of greenish color, with 

 circular alternate bands of black and white on the head and 

 pronotum parallel to the border. The wings have seven black 

 stripes, the outer one forking near the middle. 



Adults are first recorded for July 11th, and were most abun- 

 dant July 14th, becoming gradually less numerous till the first 

 of September, when they disappeared. While egg deposition 

 must occur during July or August it has not been observed. 



The larvae observed July 2 ad to 20th were about half the 

 length of the adults, fully as broad, with the surface of the body 



