Biology of the Membra cidae of the Cayuga Lake Basin 427 



In the first method, buds and small twigs containing egg masses were 

 brought into the warm laboratory and placed in wide-mouthed bottles 

 filled with water and plugged with cotton, the whole being covered with 

 a lamp chimney topped with cheesecloth. In such cases the buds opened 

 or the twigs were forced, hastening the hatching of the eggs and making 

 possible the securing of the first and second instars. This practice also 

 permitted the study of the escape of the insect from the egg and the 

 collection of egg parasites if present. In most instances, however, the 

 nymphs ched after the first or the second molt, either l)ecause of the 

 unnatural sap conditions of the twig, because they did not survive removal 

 to fresli twigs, or because a different host was required for feeding from 

 that on which they were hatched. The method was entirely satisfactory 

 for the purposes for which it was conducted, and most of the early instars 

 have been obtained in this fashion. 



For the rearing of nymphs thru all their instars it was necessary to have 

 young plants in the insectary. Unfortunately many of the species live 

 only on trees, which could not be maintained in the limited quarters 

 available for experimental work. In some cases a constant supply of 

 fresh twigs and leaves were sufficient to keep the nymphs alive, but the 

 method was not satisfactory. Fortunately, however, a number of the 

 species spend the nymphal periods on small plants, which could be grown 

 in the greenhouse. Sweet clover, alfalfa, joe-pye weed, tliistle, goldenrod, 

 aster, daisy, and clover were successfully potted and kept under bell jars, 

 and on these hosts various species were brought thru to maturity. By 

 this method it was possible to observe the process of molting and to get 

 the cast skins after each molt. These cast skins proved to be of some 

 value in making measurements. The chief difficulty experienced in this 

 method was that of maintaining satisfactory temperature and moisture 

 conditions. Under the greenhouse glass the heat often proved too severe 

 for the nymphs, and the plants if neglected even for a short period were 

 likely to wither. However, with constant care the nymphs of a number of 

 species maj' be reared successfully, but it is a question whether the time 

 records for the various molts are reliable since the conditions are undoubt- 

 edly different from those in the field. For this reason such records have 

 been used merely as a check on the field records whenever the latter were 

 available. 



