REINDEER IN ALASKA. 55 
DERMATITIS AND ABSCESSES CAUSED BY WARBLE GRUBS. 
During the fly season, in July and August, serious cases of der- 
matitis may often occur (PI. XXII, Fig. 1). In one herd of about 
2,000 animals fully 25 cases were seen. The lesions are most fre- 
quently on the hind legs above the hock, but they may also be seen 
on other parts of the body, such as the stifle, hock, knee, forearm, 
fetlocks, and shoulder, the frequency being in the order named. 
Swelling is the first symptom, followed by the death and exfoliation 
of the skin. The animals feel irritation and bite the affected parts. 
After the skin has peeled off, large sores are seen, which may attain 
6 to 8 inches in diameter. The surface of the wound may be covered 
with round, raised granulations; in other cases the flesh dies. The 
sores are evil smelling and are covered with sticky green pus 
{Bacillus fyocyaneus) . The fawns and yearlings are the worst 
sufferers. There are many cases, however, which do not progress as 
unfavorably as those described above. Many animals have been 
noticed bearing small lesions and patches of skin denuded of hair. 
These spots are undoubtedly the result of irritation, and the hair 
has been nibbled off. According to the Lapps, dermatitis is seen 
more often during the hot dry summers than in wet seasons, and is 
most frequent with close-herded animals. 
All the evidence obtained pointed to flies as the probable cause of 
the trouble. Accordingly the skin covering the lesions was carefully 
examined and numerous eggshells of the warble fly Oedemagena 
ta/randi were found. The lesions occur where most of the eggs are 
deposited, and as it is already known that after the eggs hatch the 
young larvae bore through the skin, these were also looked for in the 
sores. Numerous larvae were encountered and it was noted that in- 
flammatory tracts followed them and that they acted as dissemina- 
tors of the pus, thus enlarging the affected area. It seems clear that 
the larvae when boring through the skin, drag in the bacteria which 
happen to be lying upon it. The larvae themselves occasion some 
swelling and irritation, which favors the development of the bacteria. 
In view of the fact that cattle suffer similar effects from the pene- 
tration of the warble larvae (though in much less severe form), there 
is no doubt that this evil must be laid at the door of the reindeer 
warble fly. 
The treatment for dermatitis is surgical. All dead tissue must 
be removed and the wounds dressed with antiseptic solution, either 
lysol or sulphate of copper being excellent. If the lesions are large 
or if the joints are involved, the animal must be killed. There is 
little hope of prevention until means are found for controlling 
warble flies. But as frequent corralling of animals and close herd- 
ing during the hot weather expose the reindeer to fly attack, such 
