PLATE VI. PSYLLIDAE. 



1. Livia maculipennis Fitch, x 12. 



2. Psylla pyricola Foerster, — pear psylla, x 12. 



3. Livia vernalis Fitch, x 12. 



4. P achy psylla celtidis-mamma Riley, — galls on hackberry leaf, 



X I. 



5. Pachypsylla celtidis- gemma Riley, — galls on hackberry twig, 



X I. 



6. Calophya flavida Schwarz, — pupae on stem of Rhus glabra, 



X I. 



7. Psyllopsis fraxinicola Foerster, x i. 



Photographs 6 and 7 by W. E. Britton; others by B. H. 

 Walden. 



