472 



Illinois Natural History Survey Bulletin 



Vol. 23, Art. 5 



noticeable degree in only 0.03 per cent of 

 the 722 fox squirrels and 0.06 per cent of 

 the 353 gray squirrels examined for this 

 condition. Incidence of mange in all 

 squirrels studied was 0.04 per cent. All 

 zones were represented by the animals 

 examined for parasites. 



The degree of infestation was negligible 

 in most woodland populations, but in some 

 urban populations of both species a heavier 

 rate prevailed. Woodland squirrels show- 

 ing evidence of mange were found on only 

 two localized areas, one the pin oak bot- 

 toms near Thomson in Carroll County, 

 involving only fox squirrels, and the other 

 near Griggsville in Pike County, involving 

 both fox and gray squirrels. The first 

 area showed an infestation of 47 per cent 

 in a sample of 15 squirrels; the latter, 15 

 per cent in a sample of 94. The degree 

 of infestation in Pike County was about 

 the same in the two species. In both 

 localities squirrels were collected during 

 the breeding seasons, and in both infested 

 individuals were apparently normally ac- 

 tive. A female shot February 26, 1941, 

 on the Thomson area had bare patches of 

 skin on head, neck and back, yet contained 

 three well-developed embryos. Another 

 collected on February 17, 1945, near Mon- 

 ticello, Piatt County, had the left hind 

 foot missing and was practically devoid 

 of hair, due to mange, on the neck and 

 thoracic regions, but this animal, fig. 7, 

 likewise contained three normal embryos. 

 None of the infested squirrels were in poor 

 physical condition. 



Practically every squirrel, fox and gray, 

 was host to fleas ; many animals carried 

 the common dog tick ; less than 1 per cent 

 carried sucking lice. Dr. H. H. Ross of 

 the Illinois Natural History Survey sup- 

 plied the following notes on ectoparasites. 



The same species of ectoparasites occur on 

 both the gray and fox squirrels in Illinois. 



Ticks (Ixodoidea) 



Dermacentor 'variabilis (Say). — Taken very 

 commonly on squirrels throughout Illinois. 

 This is the common dog tick and occurs on 

 many other mammals. 



Parasitic Mites (Parasitoidea) 



Several species of this superfamily of mites 

 have been encountered on Illinois squirrels. 



Fleas (Siphonaptera) 



Orchopeas ho^vardii (Baker). — Very common 

 and frequently extremely abundant. This 

 species has been found in great numbers in 

 overwintering nests throughout Illinois. 



Orchopeas nepos Rothschild. — Taken only 

 rarely in Illinois. 



Sucking Lice (Anoplura) 



Hoplopleura sciuricola Ferris. — Taken only 

 rarely in Illinois. 



In addition to the above, chiggers undoubt- 

 edly occur on Illinois squirrels. Although we 

 have no definite records for this state, Roger 

 Williams, while at the University of North 

 Carolina, found chiggers on squirrels. These 

 chiggers belong to the mite genus Trombicula 

 and allied genera. 



In a small number of squirrels studied 

 for internal parasites, one-third of the 

 animals contained parasitic worms. Iden- 

 tification of these specimens was made by | 

 Dr. Lyell J. Thomas of the University of 

 Illinois. The following remarks are 

 quoted from his report. 



No. 1. — Female fox squirrel, Thomson, Illi- 

 nois, collected May 27, 1941: Eight cestode 

 cysts in visceral cavity, identified as Taenia 

 pisiformis. These generally occur in rabbits. 



No. 2. — Female fox squirrel, Griggsville, 

 Illinois, collected April 19, 1942: Several nem- 

 atodes from intestine ; all females, and identi- 

 fied as Impalaia sp., probably new. 



No. 3. — Female fox squirrel, Griggsville, 

 Illinois, collected August 7, 1942: One large 

 male nematode from large intestine identified 

 as Ascaris sp. (probably A. lumbricoides). 

 Has been recorded from East Indian squirrels, 

 but not, to my knowledge, from North Ameri- 

 can squirrels. Normal hosts are man and 

 pig. Closely allied species occur in skunks 

 and armadillos. 



No. 4. — Female gray squirrel, Griggsville, 

 Illinois, collected April 21, 1942: Three male 

 and five female nematodes from intestinal tract 

 identified as Impalaia sp., probably new. Two 

 female nematodes from intestinal tract identi- 

 fied as Mescistocirrcus sp., probably new. 



The four squirrels yielding the above 

 endoparasites appeared to be in normal 

 vigor, although none contained noticeable 

 fat in the body cavity. The female that 

 was host to the ascarid was reddish to the 

 point of erythrism. The uterus showed 

 five placental scars and the mammae con- 



