Over a period of seven months the weekly count per animal averaged only 27.3 adult brown ear_ticks, varying from sixteen to 41 on each. Higher counts had been anticipated in view of the apparently favorable conditions for these ticks in the area and because of the presence of East Coast fever. The same report gives average counts from other areas, correlated with rainfall, vegetation, and incidence of disease.

The distribution of the brown ear-tick in South Africa, brief_ ly summarized from Theiler's (1949) detailed study, is as follows: It is present in areas with annual rainfall above fifteen inches, provided that bush and shrub coverage is adequate. With proper dipping practices and restriction of wild game movement this tick can be eradicated*. Theiler's report should be consulted by anyone seriously concerned with this parasite.

In Kenya, where temperatures are higher than in South Africa, an average rainfall of twenty inches or more appears necessary for R. appendiculatus to maintain itself (Wiley 1953). Because various workers have so intimately associated their studies on the life cycle and their observations on the seasonal incidence of the brown ear-tick, this subject has been discussed under Life Cycle above. Other climatic factors are presented below.

Lewis (1939A) findings in Kenya corroborate Theiler's state ments for South Africa. There, the tick is absent from the plains, desert, and high plateau areas, but common, especially between 4,800 feet and 7,000 feet elevation, where vegetation provides enough shade to meet its requirements. It is of interest to interpolate here that Kajo Kaji, Yei, and Katire, from where these specimens were taken in the Sudan, are at about 3000 feet elevation; these areas are more forested than most of Torit District_7. Lewis concluded that R. appendiculatus is active at all times of the year but more so during the rainy season, and that it thrives best when the mean maximum temperature is between 60°F. and 80°F., and the mean minimum between 50°F. and 60°F. Lewis 1931 and 1932 papers give other details of the presence or absence of R. appendiculatus in Kenya.

*A number of veterinarians believe that under most African condi tions complete eradication is impossible and while control to prevent otitis and lymphangitis should be practiced, restricted populations should be allowed to remain to induce East Coast fever immunity in calves.

In Uganda, after a series of dry years, the numbers of R. appendiculatus decrease to the point where East Coast fever is not maintained in cattle in endemic form. When the disease is introduced during the great increase of the species in abnormally wet years, the mortality of the now susceptible cattle may be serious (Wilson 1948A). It has been suggested that this tick should not be entirely eradicated in order to maintain its hosts' immunity to East Coast fever.

By way of summing up the ecology and distribution of the brown ear-tick, Wilson (1953) has designated the "R. appendiculatus - A. variegatum association" of East and Central Africa. This interesting and important contribution is reviewed herein under A. variegatum (cf. page 274; also R. pravus, page ) and should by all means be consulted by anyone concerned with the biology of the brown ear-tick. Reichenow (1941A,B), from his own observa tions in Tanganyika, has also stressed the practical importance of knowing the ecology and distribution of this parasite.

The red billed oxpecker, or tickbird, Buphagus erythrorhyn chus (Stanley), which attends all the larger herbivores except the elephant and the hippopotamus, has been shown by Moreau (1933) to be a predator of some importance on R. appendiculatus and on other economically important ticks. Of the 58 tickbirds examined in Tanganyika, almost 500 brown ear-ticks were found in the stom ach of thirty. The number of brown ear_ticks per stomach ranged from one to 96.

In Kenya, van Someren (1951) removed 59 adult and nymphal brown ear_ticks from the stomachs of eight of the same birds that he examined; none were found in four others of the same kind. He found 112 nymphs and adults in stomachs of all seven specimens of B. a. africanus that he examined in Kenya.

A further discussion of birds feeding on ticks is presented under biology of A. variegatum, page 275.

The chalcid wasp parasite Hunterellus hookeri Howard, 1908, has been found infesting nymphal brown ear-ticks removed from hares, Lepus capensis subsp., in South Africa (Cooley 1934). Cooley did not find this wasp in ticks in Kenya (Price 1948) but Philip (1954) has found it in nymphal kennel ticks there. For a brief discussion of this wasp, see biology of R. s. sanguineus, pages 710 to 712.

MAN:

DISEASE RELATIONS

Boutonneuse fever (Rickettsia conorii).

The virus of Rift Valley fever of man and animals survives only until the tick molts and is transmissible only experimentally.

CATTLE: The common, important vector of East Coast fever (Theileria parva); experimental work with the "turning sickness" form also reported. Pseudo East Coast fever (T. mutans). Red water (Babesia bigemina). Louping-ill (virus) (experimental). Not a vector of bovine infectious petechial fever (Ondiri dis ease) (virus).

SHEEP: Nairobi sheep disease, and (experimentally) loupingill (both virus).

GOATS: Nairobi sheep disease (virus).

HORSES: Louping-ill (virus) (experimental). Not a vector of horsesickness; virus is not transmitted to the progeny of ticks from fatally-infected hosts.

REMARKS

Integumentary sense organs, which are fixed in number and location, and which are essentially similar in all stages of the tick, though more primitive in larvae, have been described and illustrated by Dinnik and Zumpt (1949).

A misformed specimen has been described and illustrated by Nuttall (1914A) (repeated by most subsequent workers on the sub ject) and a gynandromorph has been reported by Santos Dias (1952E).

Schulze's work on the brown ear_tick has included certain aspects of the larval gut (1943B), of the larval haller's organ (1941), and of the external body structure of males (1932C).

Copulation has been observed by Donitz (1905) and discussed by Christophers (1906); the same remarks as for R. e. evertsi (page 652) apply to the brown ear_tick.

That the wide range of adult size and appearance (scutal smoothness, degree of punctation, depth of lateral grooves, pres ence of hairs on basis capituli, presence of dorsal concavity of palpi, shape of adanal shields, presence of accessory shields, size and shape of tarsi and of porose areas, etc.) is due to variation in fullness of feeding of the immature stages has been convincingly presented by Nuttall (1913).

It appears, however, that no matter how variable this species may be, it is seldom difficult to distinguish from other species.

When making the rather sizeable collections of R. appendicu latus at Kajo Kaji and Yei, in December of 1951, it was noted that specimens from the ears of cattle were consistently of rather uniform size and similar in structure and appearance. But specimens from sheep and goats varied considerably in size and structure, and many were malformed. Upon returning to Yei in December of 1952, additional specimens were obtained from cattle. Many of these were as variable and misshapen as the previous year's collections from goats and sheep. The factors behind these differences are too complex to allow conjecture over the reason, interesting as it might be to do so. It is suggested, however, that other reasons, besides immature stage nutrition, may drama tically influence the parasite's well-being and should be inves tigated.

IDENTIFICATION

Males vary in overall length from 1.8 mm. to 4.4 mm.; "normal" males are 3.0 mm. or above in length. They are usually brownish or reddish brown, but may be very dark; the legs are always red dish brown. The clearly-defined dorsal process of coxa I res tricts this species to a rather small group among which it can be distinguished by the deep, long lateral grooves, peculiar scutal punctation, shape and rounded posterior margins of adanal shields, flat eyes, etc. Scutal punctations of moderate size are evenly spaced in the central area of the scutum but almost or entirely disappear in the lateral fields and outside of the lateral grooves. Posteromedian and paramedian grooves are narrow but distinct and the cervical fields are more or less reticulate, especially in large specimens. A caudal process is sometimes

present. The characteristic elongate shape of the adanal shields with their slightly rounded angles is most distinctive after some series have been examined. Variation in shape of the adanal shields is illustrated (Figure 242). The basis capituli is some what variable in that the lateral margins may be more or less angled, depending largely on the size of the individual.

Females are similar to males in color and quality of puncta tions. The scutum has a distinctive outline (Figure 243) that may be slightly more narrowly rounded posteriorly than the spec imen herein illustrated; it is as wide as or slightly wider than long. The lateral grooves are frequently short or poorly defined; the transition to the raised lateral border of the scutum may be gradual or abrupt; the lateral grooves are often picked out by a row of medium size punctations. The long cervical grooves that extend, albeit shallow, to the posterior margin of the scutum demarcate oval fields beside the central field, a characteristic aspect of this species; combined with it is the moderate density of small to moderate size punctations scattered over the scutum. In small females, the punctations are frequently less numerous and the scutal surface is not so markedly divided into a central and two oval fields within a raised lateral border. The porose areas vary with the size of the individual.