Biology of the Membracidae of the Cayuga Lake Basin 377 



incomplete metamorphosis as do the Membracidae, and in this report 

 the term is discarded. In tliis instar the nymph attains a size comparable 

 with that of the imago. The pronotal developments are very pronounced 

 and the wing pads are fully formed, usually reacliing the fourth abdom- 

 inal segment. The spines are heavy but generally rather simple. The 

 head is much deflexed or prone, and eyes, ocelH, and antennae are normal. 

 The beak is fully developed, generally extending posteriorly as far as the 

 liind coxae. * The legs are strong and stout and the abdomen is swollen. 

 The anal tube is somewhat less prominent than in the preceding stages. 



The above descriptions apply of course to the familj^ in general and 

 find many exceptions in various species. On the whole, however, they 

 represent the general development of membracid nymphs. Certain 

 particular characters may be noted as of mterst and value in recognition. 

 The development of the pronotum is noteworthy as it usually gives the 

 clue to the species. Since all the local species of which the life history 

 is known have the posterior pronotal process, the gradual extension of 

 this structure is common to all nymphs. The anterior decorations are, 

 however, generally distinct, and, in the last instar at least, the vestigial 

 lateral horns of the Ceresas, the porrect spike of Thelia, the notch of 

 Entylia, and the crest of the Telamonas, are strildngly suggestive. 



The peculiar spines which are more or less characteristic of all the 

 nymphs of the family are scarcely less important. Their number, position, 

 arrangement, and type of branching are all guides in the determination 

 of the species and of the njTuphal instar. As has been noted, most species 

 show these more abundantly on tlie head and the thorax in the earlier 

 than in the later instars, and the abdominal bristles are inclined to be 

 more elaborately branched in the first stages than in the last. This is 

 not, however, always the case, for some forms retain these twig-like 

 branched appendages imtil their last molt and a few have no such bristles 

 in any of their nymphal stages. The shape of the individual spines is of 

 mterest — whether straight or cm'ved, branched or simple, long or short, 

 heavy or hglit; likewise the arrangement — whether singly or in pairs, 

 in regular or irregular row^s, opposite or indeterminable. 



The coloration of the njanph seems to be of much less value, since many 

 forms show much variation mthin the species. Size, likewise, should not 

 be taken as a criterion, except perhaps in comparison of instars of the 

 same species. 



