226 MAINS AGRICULTURAL EXPERIMENT STATION. 1916. 



carinae. Length of median spiracle about .065 mm., its width aboui 

 .015 mm. The two stigmai plates separated by a median incision. The 

 circular plates or "buttons" prominent, situated a little dorsad, .035 to 

 .04 mm. in diameter, their inner margins separated by about half their 

 diameter. The inter- spiracular ornamentation consists of four pairs of 

 prominent slender bristles or hairs (Fig. 29-.?) about .04 to .05 mm. 

 long, a pair dorsad and ventrad of the circular plate, respectively, and 

 one in each of the other interspiracular spaces. 



Puparium. (Fig. 29-3). Length about 4.75 mm., height about 2 mm., 

 width 2.25 mm. to 2.4 mm. Ventral line strongly concave, the dorsal 

 line moderately elevated, producing almost a semi-circular curve from 

 mouth-parts dorsally around to the posterior respiratory process. Great- 

 est depth and width about the anterior third, tapering moderately on 

 each side to within one millimeter of the posterior respiratory process, 

 thence rapidly to that organ, which occupies a terminal position. Nearly 

 circular in outline as seen from in front, slightly flattened ventrally. 

 Cdlor testaceous brown. Segmental and integumental spines not visible 

 to the naked eye, but giving the puparium a .spinulose appearance when 

 somewhat magnified. Other characteristics as in the larva. 



Adult. (Fig. 29-4). Uniformly black, about 6 mm. long. Antennae 

 black above, lower half of first and second joints and third joint on 

 basal half of lower side yellow ; the distal half and upper side all black. 

 Arista as long as second and third joints together. Front black pilose, 

 a few white hairs across the middle. At each side midway between 

 ocelli and base of antennae a white pollinose spot. A similar, narrow, 

 elongate stripe of the same pollen on upper part of facial orbits. Face 

 with rather sparse white pile, the eyes and posterior orbits short, white 

 pilose. Thorax and abdomen shining metallic black, finely ruguloso- 

 punctate, with very fine short white pile. Legs black with white pile, the 

 following pants yellow ; tips of all the femora, the broad base and nar- 

 row tip of the four front tibiae, the narrow base of hind tibiae and 

 basal joints of the four front tarsi. 



Melanostoma mellinum Lirme. 



One of the most common species throughout North America 

 and in Europe. Of their abundance Schiner (Fauna Austr. i. 

 291) says (translating freely) : 



"I have brought in thousands from all possible situations. They are 

 found on every trip and finally tire the poor dipterologist because, while 

 always apparently new, they nevertheless prove, upon closer examina- 

 tion to be nothing but varieties of the same variable species." 



Verrall (55. p. 311) writes: "The larva? of this species are believed 

 to be aphidophagous as they have been bred from Aphides on Chrys- 

 anthemum leucanthemum, but M. A. Giard in Bui. Soc. Ent. France, 

 1896, p. 234, traced and bred many larvae which occurred on the umbels 

 of Daucus carota (on plants which bore no aphides) and which lived 



