34 



FLIES FOUND IN HOUSES 



lateio-dorsal processes bearing spines. Ventral and slightly anterior to the base of 

 each of these processes is a small spiniferous papilla. A short spinous latero-ventral 

 appendage is situated slightly more posteriorly. Viewed from above the larva is seen 

 to be surrounded by a fringe of feather-like processes. Segments IV to XI are each 

 provided with a pair of pinnate latero-dorsal processes which gradually increase in 

 size posteriorly. Three pairs of these pinnate processes surround the obliquely 

 truncate dorsal surface of the twelfth segment. Situated laterally and ventral to the 

 series of pinnate processes is a series of latero-ventral processes which are spinous, but 

 much less pinnate and shorter than the latero-ventral series. The latero-ventral 

 processes of segment XII are situated more ventrally than those of the preceding 

 segments and their usual place is taken by a small group of spines. Posterior to the 

 base of each of the latero-dorsal processes of segments V to XI is a small branched 

 process. 



Fig. 1 6. 



Fig. 15. Larva of F. scalaris. (From Hewitt, Report to Local Government Boards 



1912, reduced by one-half.) 

 Fig. 16. Part of right middle femur and tibia of Z-". scalaris. (From Hewitt, ryi2.) 



"On the ventral side of the larva, extending from segments VI to XI there is a 

 series of pairs of small spiniferous papillce, each of which is situated at the end of a 

 transverse row of spines. Posterior to this transverse row of spines there is a shorter 

 TOW of spines, divided into four groups. The anterior, or prothoracic, spiracular 

 processes are six or eight lobed ; the usual number of lobes being seven. The posterior 

 spiracular processes are very similar to those of F. caniculans. 



" The feathery character of the processes of F. scalaris is probably associated with 

 the fact that the larva; ueually live in substances of a semi-liquid character when such 

 processes will be more advantageous than those of /'". caniadaris for life in such a 

 medium" (Hewitt, ix, 1912). 



" Prior \Q pupation the larva leaves the moist situation for one of a drier character, 

 iind the pupation is similar to that of F. caninilarisT 



