DIPTERA. 355 



( Cylindrocera, Lioy. 



" AsniOXDVLIA, Lw. = ■{ ^ ^n 



( Phyllophaga, Kd. 



" Antennas with short liairs of ei^ual length ; joints cylin(h-ical and 

 sessile ; no verticils. Same number of joints in $ and ^ . Second 

 longitudinal vein reaches the margin of the wing, beyond its tip. 

 Wings shiny." 



As the insects in the family are so very small in size, it might be 

 best for practical purposes to consider them according to the injuries 

 they inflict on the respective arboreal food-plants — viz. : 



(1) Foldings and rollings of leaves. 



(2) Galls on leaves. 



(3) Galls on stems or stalks. 



(4) Various injuries or deformities of shoots, &c. 



It is, however, not practicable to attempt reconciling this arrange- 

 ment with systematic classification. 



Hitherto this family has not been very carefully studied in forest 

 entomology, and the chief points for the discrimination of species are 

 very minute, so that recourse must be had to the microscope. The 

 main points are, the " breast-bone " in the larval stage — an " anchor 

 process " found on the first thoracic segment ; the venation of the 

 wings ; and the genitalia of the males. 



By stupefying the insects with chloroform we can very easily 

 examine with the inch objective. It is necessary to do this, how- 

 ever, in order to carefully note all the characters, more especially as 

 they change colour rapidly after death, and they are most fragile to 

 mount as microscopic slides. 



Cecidomyia (Dasyneura^) marginemtorquens, Winn. 



This insect is found on the common osier [Salix viminali^), and 

 forms galls on the edges of the leaves, — often on both sides of the 

 leaves, — and rolled from the base to nearly the apex (fig. 321). These 

 galls or foldings are on the under side of the leaves, and rolled towards 

 the midrib. The rolled portion of the leaf is generally smooth, and 

 of varying shades of colour, from pale-green to purple and chocolate- 

 brown. The galls appear early, and may be found from June to 



^ The generic names given in parentheses are those usually adopted at the 

 present time. I am indebted to Mr Theobald for this improved arrangement. 



