ABIA FASCIATA. 37 



The < wants the white band on the metathorax. 

 The eyes almost unite above, there is a bushy tuft of 

 long hair on the front, the colour of the abdomen is 

 more obscure, wanting the brassy tinge, except at 

 the apex, which is shining. The apical segment has a 

 furrow in the middle on the apical half; the band in 

 the wing is somewhat less, and the apex is clear 

 hyaline. 



Zaddach (I. c.) says the # has a quadrate black spot 

 on the fourth to seventh segment as in Abia, but this 

 is not the case. 



Not having had an opportunity of observing the 

 habits of the insects and their larvae myself, I give 

 Dr. Osborne's excellent description of their economy, 

 quoting his remarks almost verbatim. The eggs are 

 laid singly in mines formed beneath the upper epidermis 

 of the leaf, and, being inserted at the edge of the leaf, 

 form a sort of beading round its circumference. In 

 oviposition the fly sits on the edge of the leaf, holding 

 it firm with the spines on the posterior tibiae, and it 

 also uses the hinder angles of the valves of the saw to 

 hold the leaf steady at the very point where the 

 extremity of the saw is to be first introduced. The 

 ovipositor being inserted under the epidermis is first 

 thrust backwards, parallel with the edge of the leaf, to 

 its full extent, and then swept round till it lies again 

 under the edge of the leaf in front of the point of inser- 

 tion, which is situated rather behind the middle of the 

 mine ; the saw all the time playing with short, quick 

 strokes, which gives it somewhat the appearance of 

 watchwork running down. The ovipositor is next 

 brought back to a position midway in the mine and at 

 right angles to the axis of the fly ; and after a short 

 delay the egg descends between the two blades with 

 its long axis also at right angles to that of the fly. 

 The egg is green in colour, and in shape crescentic, 

 with the horns rounded off, while in the blades of the 

 ovipositor the lowermost end (in advance) would corres- 

 pond with what should be the posterior or caudal end, 



