66 BULLETIN 1089, L T . S. DEPARTMENT OF AGRICULTURE. 
as are seen in sheep, a form of dizziness induced no doubt by the irri- 
tation caused by the larvae. Bergman mentions a disease called 
" varka " in Lapland which he attributes to Cephenomyia nasalis 
and which he says may cause death. 19 In Alaska there are no rec- 
ords of reindeer dying from grubs in the nose, but it is quite possible 
that occasional deaths do occur. 
After the larva has fallen to the ground it pupates rapidly, in five or 
six hours as a rule. It differs in this respect from Oedemagena 
tarandi, which is much slower. The pupal period is shorter than it 
is for 0. tarandi. According to Bergman, the pupal stage may be 
from 16 to 31 days. In observations made in Alaska, the pupal 
period lasted up to 56 days, but this was under adverse conditions, 
and only 20 flies emerged out of a total of 54 pupae. 
The treatment or prevention of nostril flies seems even more 
hopeless than is the case with warble flies. The only means of pre- 
vention that seems at all likely to succeed would be to provide dark- 
ened shelters for the reindeer to go into when the flies are attacking 
them. In northern Europe, especially on the Finnish side in Lap- 
land, long dark sheds are provided, and the Lapps say that without 
such protection reindeer would suffer greatly in some districts. 
Shelters would be most helpful against the warble fly as well and 
would also afford the reindeer some protection from other forms of 
insect life. Unfortunately, in' arctic latitudes the insects are at 
work the greater part of the 24 hours ; consequently, during the hot 
weather the reindeer might not get very much chance for feeding. 
But on the other hand, if the animals have no means for protecting 
themselves they suffer so much annoyance and worry that the loss 
of a little food would seem preferable. 
Lapp names for Cephenomyia nasalis are as follows: The larva 
is called saula ; and the imago or fly, boaro. 
SCREW WORMS (PHORMIA TERRAE-NOVAE) . 
Blowflies are found in abundance on all the reindeer allotments. 
Both natives and whites are careless in the disposition of refuse ; con- 
sequently, on approaching a reindeer herder's cabin, swarms of blow- 
flies may be seen rising from rubbish heaps containing reindeer offal, 
fish refuse, and other offensive material. Keindeer that die on the 
range are usually left where they lie. It is no wonder, therefore, 
that wounds may become infected with screw worms. A heavily 
infected skin taken from a reindeer on May 20 is illustrated in 
Plate XXII, Figure 2. 
The most important factor predisposing reindeer to infestation 
with screw worms in the warble fly. When the warble larvae emerge 
19 Bergman, Arvid, On the Oestridae of reindeer : Entomologisk Tidskrift, vol. 38, pp. 
1-32, 113-146, 1917. 
