8i 
a small dentate sclerite ; the hypostomal sclerite articulates with two 
large bifurcated cephalo-pharyngeal sclerites, and in front of the upper 
arms of these pates is a small perforated sclerite. In a freshly- 
prepared specimen both the retractor and extensor muscles to these 
sclerites can be distinctly traced. Ventral surface of the last seven 
segments furnished with raised bands of tactile tubercles. Posterior 
stigmata two in number, circular ; thoracic stigmata placed sub-Iaterally 
on the third segment, each consisting of apparently- five circular 
orifices, these are connected posteriorly' with a large bilateral air sac 
which extends along the fourth segment. 
Length of adult, 11 mm. 
Young larvae are much more transparent and glass-like, and the 
large anterior mouth-hook is not developed, a blunter process taking 
its place. 
Habits of the Larvae. — They move rapidly along a smooth 
surface, pulling themselves along chiefly by means of the large mouth 
hook ; and proceed practically in a straight line, moving the head 
rapidly but irregularly from side to side or up and down. There is, 
however, no regular alternate movement of the head during progres¬ 
sion as in some muscid larvae. Their progress through the burrows 
in their food is much more rapid than on a smooth surface, and when 
disturbed they disappear with extraordinary rapidity. The larval 
stage lasted, under favourable conditions, from 14 to 21 days; but the 
absence of excessive moisture and the admission of a little light 
materially retarded their development, which then extended over a 
period of from 31 to 78 days.* The larvae exposed to such conditions 
produced much smaller pupae and correspondingly small imagines. 
Method of Pupation. — This is completed in about two hours 
At first the larva rapidly shortens itself, chiefly by contracting the 
anterior segments, and becomes barrel-shaped. At this period it is of 
a creamy-white colour, and the mouth parts of the larva are still visible 
through the soft integument. The colour rapidly changes to bright 
ochreous, and in the space of two hours or even less, the integument 
hardens and the puparium assumes its normal colour. In cases where 
soil was placed below the faeces the larvae generally burrowed into 
the former to a depth of about half an inch, but a few also pupated 
* A few specimens still remain in the breeding cage, and may nossihlv nas- th< 
winter in this stage. 
F 
