280 CALIFORNIA FISH AND GAME 



blown out of the internal nares and tui'binal passages of the deer. In 

 extreme cases these parasites work up through the turbinal passages 

 of the deer's head and have been known to penetrate nearly to the brain. 

 In other instances they cause inflammation, and some drop down into 

 the anthrum where they cause infection and sometimes even the death 

 of the host. 



It has been suggested that if large auger holes were bored in salt 

 logs and filled with salt and the sides of such holes smeared with pine 

 tar, the deer might in getting salt also collect enough pine tar on their 

 noses to prevent ovipositing of the bot flies. The bot fly larva is a 

 serious and widespread drain upon our mule deer, but corrective 

 measures are difficult to apply. 



The commonest external parasite of mule deer in California is the 

 woodtick {Dermacentor occidentalis), which is given bj^ Essig {Insects 

 of Western North America, 1926, p. 21) as the "most abundant tick 

 on the Pacific Coast and the deer is the preferred host. ' ' He also states 

 that this is the tick commonly acquired in brushy areas in central 

 California. California mule deer are often heavily infested with these 

 ticks. In Yosemite on July 6, 1929, I counted 50 woodticks on an area 

 4 inches square of thin skin on the inside of a doe's leg (see Fig. 101). 

 In winter when the deer are in full coat the presence of woodticks is 

 often revealed by the irregularities in the pelage. This was particularly 

 noticeable in a doe observed and photographed in Yosemite Valley (see 

 Fig. 109). By close observation I found that woodticks tend to gather 

 where the deer have difficulty in reaching them, as at base of tail (see 

 Fig. 110), at base of ears, and on the neck. However, the deer circum- 

 vent the ticks by biting them on each other (see Fig. 83). Thus in 

 Yosemite on July 13, 1928, I watched two does standing side by side 

 nibbling ticks on each other. By watching with binoculars at close 

 range I saw one doe reach over and nip a large woodtick off her com- 

 panion's body, just behind the front leg. Having pulled the tick off 

 with her incisor teeth, the doe gave it a few hasty bites and then, 

 instead of dropping it, she deliberately swallowed it. The habit of one 

 mule deer biting ticks on another is common to both sexes and to all 

 ages from fawns to old bucks. 



The woodticks do not in themselves often directly cause the death 

 of deer, but they do tend to reduce their vitality and resistance so 

 that indirectly they contribute to the loss of deer. I know of no prac- 

 tical management method of eradicating woodticks from wild deer. 



At least two species of deer tick flies occur upon deer in Cali- 

 fornia. They are known as Lipoptena depressa and L. subidata. In 

 both the Modoc and Lassen areas deer tick flies are sometimes said to 

 infest the Rocky Mountain mule deer to such an extent as seriously to 

 weaken the mammals. However, I have never found more than a mild 

 infestation of these parasites. 



EYE DISEASE 



An infectious unidentified eye disease, resembling but seemingly 

 different from pink eye, has been found common at times in California 

 mule deer. In Yosemite on December 10, 1927, I found a spike buck that 

 had an infected eye. Many of the young deer in Yosemite contracted 

 this disease that winter. A characteristic symptom is the covering of 



