378 



W. D. FUNKHOUSER 



In general the nymphs of each genus show some character which is more 

 or less distinct. The Ceresas and the Stictocephalas may be known by 

 their bristling, forest-like growth of branched dorsal spines; the Carynotas 

 by the lack of such spines and the crescent-shaped pronotum; Acutalis 

 and Micrutalis by the fact that the abdominal spines lie almost flat against 

 the body; the Telamonas by the very heavy dorsal abdominal teeth 

 which take the place of the spines, and by the evidence of the pronotal 

 crest; Thelia by the porrect horn on the prothorax; Cyrtolobus by the 

 smooth body and the rounded thorax; Ophiderma by the small size, the 

 hairy appearance, and the flattened dorsum; Campy lenchia l)y the broad 

 abdominal median dorsal plates; Entylia by the prominent notch on the 

 pronotum; and Vanduzea by the straight dorsal line and the peculiar 

 anal tube. 



The time required for each nymphal instar varies not only for the differ- 

 ent species, but also for the nymphs of a single species and even for the 

 individuals in a single egg mass. For this reason the general subject of 

 nymphal periods can be discussed only roughly. In general, however, 

 it may be said that the average for each of the first four instars is about 

 five days and for the fifth instar ten days, making a total of thirty days 

 for the complete period of development from egg to adult. This may be 

 shown for some of the more abundant of the local forms by the following 

 table of averages. 



Enchenopa binotata . . . 



Ceresa diceros 



Ceresa bubalus 



Ceresa taurina 



Ceresa borealis 



Stictocephala inermis . . 



Thelia bimaculata 



Telamona reclivata .... 

 Telamona unicolor .... 

 Telamona ampelopsidis 



CyrtolobiLS van 



Vanduzea arquata 



Entylia bactriana 



Third 



instar 



6 days 

 5 

 7 

 7 

 9 

 8 

 6 

 8 

 5 

 10 

 5 

 8 

 5 



Fourth 



instar 



8 days 



5 



7 

 10 

 10 



9 



6 



7 

 10 

 10 



5 



4 



5 



Fifth 

 instar 



10 days 



8 

 14 

 15 

 12 

 13 

 11 

 12 

 14 

 15 

 10 



8 



8 



