24k Canadian Arctic Expedition, 1913-18 
brown pigment were scattered regularly in the furrows between the body- 
tubercles (spine-carriers). 
From this latter stage there were all grades of transitions to the dark pupae 
(pre-pupse) (see below) ; the main colour of the larvse changing gradually from 
white to a dirty brown, and finally to almost black (post-larvse, pre-pupse), the 
body tubercles being most strongly coloured in all the larvse; the chitinous parts 
also become black. In the black-brown post-larvse (pre-pupse) the colour of 
head, spiracles, and body-spines shades into that of the whole larva. 
A shortening of the larvse now takes place, the terminals being retracted, 
so that the segments lie telescopically one inside the other. The body-spines 
and body-tubercles, formerly so pronounced in full grown larvse, seem to shrink 
in, so that the segments are smoother and the transversal diameter of the post- 
larvse increases until it is almost as large (about 17 mm.) as the longitudinal one. 
The larval skin dries and becomes more chitinized and stiffer, so as to protect 
the pupa inside. Of the post-larvse only six were found in three skins; and the 
black colour of the pupa shows through its enclosing cyst, though the cyst is less 
pronounced than in the younger larvse, because the grub lies half-protruded 
from its exit-hole, hidden by its host's hairs. A few of the exit-holes were already 
empty (except for the grub excrement) and the cj^st inside (formed by the inner 
part of the caribou-skin around the larvse) had become contiguous to the sur- 
rounding skin. 
In spite, therefore, of all the annoyance and pain caused by these grubs, 
it seems that the caribou skins heal quickly after the parasites drop out. By 
the end of June no grubs are in the skin, the holes they made are almost healed 
and it may be assumed that the pupse leave the caribou about the end of May 
and he on the ground for about a month before the flies appear. Life in the latter 
stage is probably only short and exclusively devoted to copulation and the 
laying of eggs on the caribou's hairs, after which the grubs bore through the 
skin. 
The other dipterous parasite of the caribou is also an oestrid, identified 
by Mr. J. R. Malloch as Cephenomyia sp. and was noted at the end of May, 
1916. About twelve grubs 2-3mm long were lying in the nasal passage of the 
caribou, where they can easily attach themselves by the aid of their mouth- 
hooks and hang suspended. The smallest ones were white-yellow, with red- 
brown segmentally arranged spinehooks, black jaws, and anal spiracles. The 
older ones had the spines darker, and grey-black dot pigment on the dorsal side 
of the body segments. The oldest ones had still more black pigment (especially 
behind and ventrally) and still darker spines. Efforts to rear the larvse were 
unsuccessful. 
This is probably the Tdbanus larvse about which Grenfell writes and which 
he figures in his book on Labrador. The eggs are laid in the nostrils of the 
caribou, and the grubs probably spend all their time in the nasal, bronchial 
and oesophagel passages of their host. 
June 1-10, 1916 
A weevil (Lepyrus palustris) was found on June 4, and the first bumblebee 
(Bomhus hyperhoreus) was observed. The ponds yielded midge and large 
dipterous larvae. Some of these latter have a habit of mud-burrowmg, but one 
species seems to be more dependent on air, for it occasionally comes to the 
surface with the five long, ciliated appendages that surround the spiracles 
spread in star-like fashion. The adhesion of the surface and the hairy append- 
ages appears to be sufficient to keep the whole larvse suspended. In this 
position they may frequently be seen burrowing head first in the mud of shallow 
water. Dytiscid beetles and a small brick-red water mite were noted. On 
June 8 three caterpillars, collected at the harbour, were placed for rearing. 
One, a large naked larva, had evidently been washed out from its feeding ground 
