The Scottish Naturalist. 255 



not always seen, above the shoulders, which are themselves 

 paler ; some largish fuscous or black points at the base of the 

 black bristles, which are rather stout; scutellum and metathorax 

 unicolorous. Abdomen not much narrower than the thorax, 

 longish ovate, very convex, tapered to the apex, pale grey, with 

 some rubbed darker specks, and a distinct black dorsal line, 

 seen in certain aspects as far as the tip, but more conspicuous 

 on the first and second segments; the anal segment small, 

 shining black ; the segments with a considerable scattered stiff 

 pubescence, and a row of long curved bristles before the hinder 

 margin of each. Legs black, slaty on the femora above ; the 

 fore and hinder femora subpectinated above and beneath with 

 longish black bristly hair; the middle with few only, and two 

 curved ones near the apex ; hinder tibiae with about twelve 

 spines, placed in different directions ; the middle with about 

 ten, mostly encircling the apex ; the fore ones with five or six ; 

 the foot-pads small, whitish beneath, duskier above. Poisers 

 yellowish ; wing-scales moderate, tawny ; wing rather yellowed, 

 particularly towards the base ; the nervures tawny towards the 

 base, outwardly brown, the costal one darker, fringed with 

 wideish short bristles, and bearing a longish spine ; the first 

 cross nervure slanted ; the second almost erect and nearly 

 straight. Length 2^-3 lines ; expansion of the wings 6 lines. 



The fly is very common on the flowers of the ragwort during 

 the first and second weeks of August. 



In September the maggot is prevalent everywhere in the rag- 

 wort flowers, and also in those of the marsh ragwort ( Senecio 

 aquaticus). It destroys the seeds and the receptacle, blacken- 

 ing where it does not devour, and matting the florets together 

 round it as a safeguard from parasites, and sometimes piercing 

 through the receptacle into the stalk. Those flowers that hold 

 them are distinguished by a brown spot on the disk, and the 

 premature fading of the central flosculi. 



The maggot is dirty white, subopaque, with a testaceous clearer 

 stain along the back posteriorly ; very minutely roughened or 

 wrinkled, as if shagreened ; thickish, spindle-shaped, tapered 

 anteriorly, and narrowed slightly behind ; the segments pretty 

 distinct ; a series of foveas along the sides ; the two oral hooks 

 short, the tips only appearing ; each above overlapped with a 

 slight pointed fleshy peak; the tracheae pretty distinct ; the an- 



