-s 1920] MetcalJ-Oshorn: Insects of Between-Tide Zone 109' 



Tibicen viridifascia Walk. 



Adults of this species occurred in the grasses of the tidal 

 ■ flats of the Wrightsville Beach on the bay side of the dunes- 

 and in many instances the specimens taken were at points 

 evidently below the high tide level. Pupae were found in con- 

 siderable numbers attached to the grasses well below the level 

 of high tide and very evidently where they had been attached 

 for the emergence of the adults. Holes were observed at points 

 well below the high tide level which had every appearance of 

 being the openings from burrows which had been occupied by 

 nymphs as they were in the same localities where exuviae were 

 clinging to the stems of grass. Further there were many pupal 

 cases in the drift and these would appear much more likely to- 

 have come from a level below tide than above as otherwise it 

 would have been necessary for the cases to have been dislodged 

 from the grass and blown to the surface of the water. From 

 these observations we feel warranted in the conclusion that 

 the nymphal stages of this species are passed in soil that is for- 

 a large part of the time under water in fact only exposed at 

 times of low tide. 



A little search for egg punctures was rewarded by the finding 

 of such punctures in the stems of the Uniola which had every 

 appearance of Cicada punctures and later these were proved 

 both by dissection of eggs from females and on hatching to be 

 such. The egg punctures occurred mostly at a height of two to 

 three feet above ground and in the third or fourth internode 

 of the stem and for all observed at such a level that they were 

 above the level of high tide unless possibly for exceptional high 

 tides. The fresh punctures which were the most abundant ones 

 found occurred in the old stems of the grass apparently stems 

 of last year's growth but in one instance an internode of an old 

 stem contained egg punctures apparently of a former year as 

 well as fresh ones just completed. 



The adults fly promptly when disturbed. 



The Cicadellidce are essentially plant feeding insects adapted 

 to living upon the leaves or stems of their food plants and the 

 species occurring on the tidal flat grasses have undoubtedly 

 adjusted themselves to this condition from ordinary habitats, 

 in all probability simply following the host plant as it has 

 become adapted to this special ecologic condition; an adapta- 

 tion for both plant and associated insect that must represent 

 the play of ecologic forces through a great lapse of time. 



