NOTES ON DIPTERA. 1 1? 



Art. XVI. — Notes, ^c. upon Diptera. By A. H. 

 Haliday, M.A. 



1. Notes upon Diptera. 



The leaves of the holly often abound with the larvas of 

 Phytomyza ohscurella (Fallen, Phytom. 4, No. 8), which 

 mine below the cuticle, producing patches like blisters. The 

 puparium is much flattened, of eleven segments, and light 

 chestnut in colour. When the fly is ready to come forth, 

 its parts may be distinctly seen through the case, the eyes and 

 wings being dark, the rest pale ; only the hairs of the thorax 

 have their full blackness, and are laid flat on the back. The 

 eyes of the fly lie at the fourth segment of the puparium, 

 the first three being occupied by the frontal vesicle. When 

 the fly is about to emerge, these segments split down each 

 side from the double point (i. e. the anterior spiracles) to the 

 eyes, and the vesicle is protruded and inflated, assuming 

 various forms, and being at intervals contracted and wrinkled. 

 When at its full extent it is almost as large as the thorax. 

 It is entirely composed of a soft skin, minutely punctured, 

 without hairs or inequalities. When the fly has nearly got 

 free, the vesicle is contracted about the middle, so as to show 

 the true form of the head ; and its exterior pouch is soon intro- 

 verted and withdrawn into the head, the two transverse lines, 

 or wrinkles, at which it was strangled, being applied to each 

 other, and forming the suture which separates the front from 

 the face. When the fly is emerging, the halteres are inflated, 

 and the antennae reclined, with the arista pointed under the 

 eye. The hind-legs are used to wipe and develop the wings. 



Phytomyza fiaviceps (Macquart, S. a B. II. p. 616, No. 3), 

 was bred from subcutaneous larvfE in the leaves of woodbine, 

 by Mr. G. C. Hyndman, from whom I received specimens of 

 the fly. 



For some seasons past, Mr. Hyndman has found plants of 

 Veronica chamedrys, with the opposite leaves connected all 

 round by their edges, forming an oval case, containing the 

 larva of a Cecidomyia. The fly has the two posterior ner- 

 vures of the wing connected near the middle, and in other 

 respects seems identical with C. bicolor. 



