174 IOWA ACADEMY OF SCIENCES. 



Some of the results which seem to be general in nature may 

 toe mentioned here. 



The species of Jassidso have, as a rule, a decided limitation 

 as to food plant/, usually holdirg closely to one species of plant, 

 almost invariably iimited to one plant for breeding, but feeding 

 more indiscriminately in maturer stages. 



So far as kcown, all the species deposit eggs upon the stems 

 Tindir the leaf sheaths or in the leaves of the plants used as 

 iood. 



There is a -wide difference in life-histories, some having one 

 brood, the majority of the grass-feeding species two, and still 

 others three in a season, and the successive stages occurring at 

 widely different times. 



Except in the case of adult hibernation the ordinary life of a 

 brood of adults does not exceed two months, and for the indi- 

 viduals of a brood rarely over one. The males appear a week 

 to ten days before the females and disappear as much earlier. 

 In general, one brood of adults will have disappeared before 

 the larvse of the next have matured, so that individuals col- 

 lected at any time may be referred with assurance to a partic- 

 ular brood. 



It follows also that eggs for each brood are deposited within 

 a limited time and that a period may t e defined during which 

 all eggs of a given brood for a given species will have been 

 deposited, and during which time measures for their destruction 

 may be applied. 



Observations were made to ascertain whether simply cutting 

 the grass and leaving it in the field would prevent hatching, and 

 In no case were eggs observed to hatch from stems cut green. 

 Part of the stems from a plant in which eggs were fully devel- 

 oped were cut and left to dry. Tiie second day after the eggs 

 hatched in the uncut stems but no larvse issued from those that 

 were cut and, on examination, the eggs were found to be crushed 

 and distorted from the shrinking of the plant tissues and by 

 the curling of the edges of the sheaths in drying. Even if 

 hatched they would have been unable to escape from the rigid 

 incurved edge. 



It has been learned that the larvj© present definite characters 

 which are of specific, and in some cases generic, value. These, 

 along with what prove to be constant characters in large series 

 of adults, enable us to combine some forms hitherto considered 



