177 



PiopUla luteata, Hal.— There is no doubt that this and pectoralis, Zett., 

 are the same species as Haliday pointed ont in Walker's Ins. Brit. Dipt, iii, 

 p. xiii (1856). Walker was wrong in calling it " The Bacon Fly" and quoting 

 vetasionis, Duf., as a synonym. P. casei, L. (of which petasionis, Duf., is a 

 synonym) is the "Cheese and Bacon Fly." I have bred it from cheese and 

 caught it on bacon hanging up in a house. 



PiopMla vulgaris, Fin.— This is the species standing in the List under the 

 name atrata, F. No one has satisfactorily differentiated atrata, ¥., from 

 casei, L. Meigen's atrata is certainly true casei, and Zetterstedt had casei 

 mixed up with vulgaris, Fin., under the name atrata, according to specimens m 

 his collection ; I therefore agree with recent authors in sinking atrata, F., as a 

 synonym of casei, L. In Fallen's collection, under the name vulgaris, I found a 

 pair of the species to which I now restrict that name, and a male nigriceps 

 evidently answering to the black-headed variety of vulgaris mentioned by 

 Fallen in his description. 



PiopMla nigrimana, Mg., I consider this and affinis, Mg., to represent the 

 same species. 



PiopMla apii, Westwood, was described in the " Gardener's Chronicle," 

 1848, as follows: "Thorax and abdomen entirely jet-black and very glossy, 

 « with a slight brassy tinge and with fine golden-grey hairs scattered about 

 " the body. The head is chestnut coloured, paler near the mouth, and black in 

 " the middle above ; the eyes and the club of the antenna are pitchy, the 

 " bristle of the latter luteous. The legs (including all the coxae or joints by 

 " which they are attached to the body) are very pale straw-yellow, the tarsi 

 " especially of the hind feet somewhat more dusky. The wings are entirely 

 " hyaline or colourless and the veins very pale buff. Larvae in solid part of 

 " stalk of celery." No one has ever recognised the species, and I cannot help 

 thinking that the description applies better to a species of Psila. 



The following Table will give some idea of my intei-pretation of the eight 

 species of PiopMla in the British List : — 



1 (6). Humeral and presutural bristles present, mesopleura3 bare, one pair of 



fronto-orbital bristles strongly developed. 



2 (3) Face and frons black, legs yellow, except front tibiae and tarsi and end 



of front femora ^«*^^^«' ^S' 



3 (2). Face and frons yellowish. 



4 (5) Humeri and pleurae extensively reddish-yellow luteata, Hal. 



5 (4). Humeri and pleurae black vulgaris,mn. 



6 (1). Hmneral and presutural bristles absent, fronto-orbital bristles small 



or absent, mesopleurae hairy (except in nigriceps). 



7 (8). Thorax dull and bare with only three lines of small hairs ...casei, L. 



8 (7). Thorax shining with scattered pubescence. 



9 (12). Face and frons black. 



10 (11) Antennae yellowish, mesopleurae bare nignceps, Mg. 



11 (10). Antenna, black, mesopleurcB hairy nigricornis, Mg. 



12 (9). Face and frons yellowish. 



