Biology of the Membra cidae of the Cayuga Lake Basin 383 



Basin will be worthless when applied to other localities. As is noted 

 later under the subject of ecology, even the variations found in local 

 weather conditions have had their effect on the number of generations 

 in a season, and it is reasonable to conclude that the number is not con- 

 stant over a wide territory. 



Even locally the estimation of the number of broods for the great 

 majority of species must be based only on observations made in the j&eld, 

 since it is impracticable to maintain in the laboratory or the insectary the 

 necessary hosts for oviposition and feeding thruout the year. Further- 

 more, the overlapping of the stages of nymphal development, and the 

 consequent prolongation of mating periods after maturity with the 

 resulting variation in periods of oviposition, make it impossible to state 

 the exact number of days that may be assigned to each generation. 



In the case of species having two or more generations a year, such 

 as Vanduzea arquata and Entylia badriana, the field records are made 

 with great difficulty as it often happens that nymphs of all stages and 

 adults of all ages may be collected from one host practically thruout 

 the entire summer. 



wintering over 



Careful search has been made for evidence that membracids winter 

 over in any other form than the egg stage, which is certainly the normal 

 method. The results seem to show that Entylia badriana and Publilia 

 concava pass the winter as adults, and that occasionally Cyrtolobus vau 

 may do likewise. These conclusions have been based on the fact that 

 imagoes of these species have been found hibernating in soil and forest 

 litter during the winter months and have become active on being brought 

 into the laboratory, and the fact that adults have been collected in the 

 spring at dates so early as to preclude the possibility of nymphal develop- 

 ment. The usual methods of investigation have been to sift the earth 

 and debris beneath the plants Avhich the insects are known to inhabit; 

 to make exammations of the leaves and the bark of such hosts during 

 the winter; and to make early spring and late fall collections in order to 

 note the stages taken. 



It would appear from such investigations that the above-named species 

 are the only ones that sui'vive locally in the imago stage. If any others 

 have similar habits they have not yet been discovered. 



