536 Observations on Habits and Parasites of Common Flies 
“ When fully inserted it remains in that position for perhaps a min ute 
when she withdraws the ovipositor about one-half its length, and again 
pushes it in. This procedure may occur several times, until at last she 
withdraws the whole ovipositor, and it springs back to its former groove. 
“ The only evidence of a puncture remaining is a small bead of clear 
fluid at the point of insertion, but she almost immediately afterwards 
turns round and sucks up the liquid, and thus leaves no visible signs 
of her work. 
“This liquid is probably used in the first case as a lubricant by bathing 
the styles as they work on the sheath while puncturing. 
“The time occupied in the whole process of insertion and partial 
withdrawal and deposition of the eggs is variable, and was found to 
range from four to twenty-five minutes. Several attempts may be 
made to insert the ovipositor before deciding upon the final spot, the 
choice of which appears to be aided by the tactile hairs present on the 
apex of the abdomen. 
“The eggs are white, elongate oval objects measuring -35mm. in 
length and -14 mm. wide and are laid between the pupal capsule and 
the enclosing integument of the developing fly, the latter not being 
punctured by the ovipositor as might be expected. They are found 
associated in clusters of about ten, but sometimes groups of four and 
varying numbers up to and over ten may be found. 
“ The eggs appear to be coated with a trace of some sticky substance, 
which causes them to adhere together and to the covering integument 
of the fly pupae. The eggs remain attached to the integument during 
embryonic development. The young larvae hatch in about three days’ 
time, when they measure about -3 mm. in length. They bite through 
the fly integument, insert the head, and while their bodies remain 
outside, feed upon the juices of the fly pupae. 
“ As the larvae develop the unfortunate pupae are gradually eaten, 
until the full-grown parasite larvae occupy the space occupied by the 
fly pupae, nothing of the latter finally remaining except the shrivelled 
integuments. 
“ The period of development of the larvae occupies about seven days 
from the time of hatching. The full-grown larva is a cylindrical, 
dirty-white, legless grub, approximately 2-4 mm. long and 1-4 mm. 
wide, thickest in the centre and tapering towards the extremities. 
“ The pupa is at first whitish in colour, with prominent eyes of reddish- 
brown, the legs and wings plainly visible, and the whole body enfolded 
in loosely-fitting skin, through which the outlines of the future perfect 
