200 Annals Entomological Society of America [Vol. VI, 



The Larva. Plate XXII, Figs. 2 and 3. 



Color creamy white to yellowish, shiny, greasy in appear- 

 ance. The coiled alimentary tract, when filled with food, 

 gives the posterior portion a dark appearance. The longitudinal 

 tracheae may be recognized as two submedian white lines 

 which show delicate lateral branches. The posterior stigmata 

 are black, while the thoracic ones are yellowish in color. 



In form the larva is elongate, tapering towards the head 

 but broadly rounded behind. The segmentation is not very 

 conspicuous, and the epidermis is bare, not having hairs nor 

 bristles. On the head may be seen two large divergent mam- 

 miform processes, at the end of which are the minute retractile 

 antennae, which are apparently each composed of four sub- 

 equal segments. The mouth parts are strongly chitinised in 

 the full grown larva and are composed of a number of sclerites 

 as shown in Figs. 2 and 3. 



The last seven segments are furnished, on their ventral 

 surface, with raised bands of tactile tubercles. The posterior 

 stigmata are two in number, circular, and somewhat distant 

 from each other. The thoracic stigmata occupy a sub-lateral 

 position on the third segment, and each consists of five cir- 

 cular orifices, (t. s.). These are connected with a large bilateral 

 ,air sac which extends along the fourth segment. 

 Method of pupation. 



The time taken for pupation is usually about two hours. 

 The larva at first becomes quiet, and shortens rapidly, chiefly 

 by the contraction of the anterior segments. In this way it 

 assumes a form which resembles a barrel in shape. At this 

 stage it is still yellowish white and the mouthparts of the larva 

 are plainly visible through the soft integument. The color 

 then changes to a bright yellow, and in about an hour longer 

 it assumes the normal chestnut color of the puparium. 



The puparium is from 5 to 6 mm. in length, only eleven 

 segments are visible, the anterior one bearing the minute, 

 bilateral, thoracic stigmata, while the broadly rounded posterior 

 segment shows the disc-like posterior stigmata. Under opti- 

 mum conditions this stage lasts from 9 to 13 days. 

 Development of the adult. 



About three days before the emergence of the adult fly, 

 the cuticle of the puparium darkens, and eventually splits 

 along the lateral and median lines, anteriorly, and trans- 



