Kenneth M. Smith 179 



an attacked plant the pupae may usually be found in the cavity thus 

 created. 



Description of Puparium. The puparium is oval in shape, dark brown 

 in colour, occasionally varying to a lighter colour, and 6 or 7 mm. in 

 length. The larval structures are retained and can easily be made out. 

 Fig. 5 is a photograph of the puparium. 



Duration of Pupal Period. The following observations were made 

 with numbers of larvae in order to determine the time occupied by the 

 pupal stage. 



Larvae pupated Adult flies hatched Period 



June 20th July 9th 19 days 



„ 23rd „ 10th 17 „ 



„ 25th „ 12th 17 „ 



„ 29th „ 16th 17 „ 



„ 29th „ 15th 16 „ 



This gives approximately an average of seventeen days for the length 

 of the pupal period. 



Description of Adult Fly. The male is a grey insect somewhat like 

 a house-fly in appearance, though rather lighter in colour. Its body is 

 about 6 mm. long and measures | inch across the wings. The thorax is 

 of a lighter grey than the rest of the body and has a number of large 

 bristles interspersed with small ones running longitudinally giving the 

 thorax a banded appearance. The abdomen is darker than the thorax 

 and is much more heavily set with black bristles; there is a band of paler 

 grey down the centre of the abdomen. In the male the eyes are very 

 closely set together. The female is very similar to the male in general 

 appearance, except that it is rather lighter in colour, the eyes are widely 

 separated and the abdomen is broader and pointed at the end, owing to 

 the presence of the ovipositor. 



The following description of the Onion-Fly under the name Phorhia 

 cepetorum is quoted from Meade's Descrijjtive List of the British Antho- 

 ■myiidae. 



"Head: face sHghtly prominent; epistome flat; eyes of male con- 

 tiguous; antennae of moderate length with the arista thickened and 

 pubescent at its base, but nearly bare in the middle and at the extremity. 



Thorax: with the scutellum of a light yellowish-grey colour; the 

 former marked with four indistinct pale brown stripes, and with four 

 rows of black bristles. 



Abdomen: oblong and rather narrow, cinereous, clothed with black 

 hairs and showing silvery white reflections when viewed from behind; it 

 is marked down the dorsum with a row of elongated narrow triangular 

 black spots, which form a sub-continuous stripe; the anal segment is grey, 

 small and rather pointed ; the sub-anal male appendages are large and hairy. 



12—2 



