These specimens were collected in 1949 and 1950 but subsequent ly we have been unable to find the pigeon argas in Juba or elsewhere in the Sudan. These few may have been remnants of stragglers or of a small number of introduced individuals. If it is a normal inhab itant of the Sudan, the pigeon argas is sporadic and rare here. No other specimens are known from the Ethiopian Faunal Region, except those reported by Rousselot (1951,1953B) from French West Africa and one, possibly this species, from Kenya (Heisch 1954B).

DISTRIBUTION

Argas reflexus appears to be a Near or Middle Eastern tick that has spread northward through Europe and Southwestern Russia and eastward to India and elsewhere in Asia (the status of related species or subspecies in Asia requires further study). It may have been accidentally introduced into a few localities in the Ethiopian Faunal Region north of the Equator and to parts of the Americas. If so, transportation of infested domestic pigeons undoubtedly has been responsible for this range.

NORTH AFRICA: EGYPT (El Dardiry 1935. Hoogstraal 1952A. Taylor, Work, Hurlbut, and Rizk 1956). ALGERIA (Nuttall et al 1908. Neumann 1911. Presence not subsequently verified). Unknown in Tunisia (Colas_Belcour 19298).7

WEST AFRICA: FRENCH WEST AFRICA (Rousselot 1951,1953B from Bamako, Soudan).

EAST AFRICA: SUDAN (Hoogstraal 1952A,1954B).

?KENYA: Heisch's (1954B) specimen may represent a closely related species.]

NEAR EAST: A. reflexus has been reported from Palestine (Theodor 1932), Turkey (Vogel 1927, Kurt pinar 1954) and Iran (Delpy 1947B). Its occurrence in intervening areas is to be expected.

FAR EAST: According to Sharif (1938), this tick, as variety indicus Warburton, is an important pigeon parasite all over India.

EUROPE: In Europe, A. reflexus is generally distributed and extends at least as far north as Denmark (Christiansen 1934). It occurs also in the British Isles. The Russian range of this tick is said to be confined to the Caucasus, Crimea, and areas bordering southern Europe (Pavlovsky 1948), but Olenev (1929A,B,C,1931A,B,C) also includes Middle Asia and western Siberia. Oswald (1939) did not find the pigeon tick in Yugoslavia.

AMERICAS: Cooley and Kohls (1944) list western United States and Columbia as collecting localities for ticks that they call A. reflexus but that show morphological differences of yet unknown Importance as species indicators.7

HOSTS

Domestic pigeons are the chief host of A. reflexus and are mentioned by all authors. Man is frequently attacked, especially in the vicinity of long unoccupied pigeon cotes. Chickens, horses, and (in America, see above) wild birds such as the condor, swallow, and screech owl (Cooley and Kohls 1944) have been listed as hosts. In the laboratory, any usually available mammal may serve as host.

The literature contains numerous reports of A. reflexus biting man and the painful sequelae of these attacks. Although the pigeon argas is mostly strictly associated with pigeons, the exigencies of its domestic existence drive it to attack persons, possibly more frequently than does A. persicus.

Early literature concerning the pigeon argas as a parasite of man has been reviewed by Nuttall et al (1908). More recently, Kemper (1934) attributed four cases in Germany to the effects of warm weather. Kemper and Reichmuth (1941) reviewed the literature and reported over twenty attacks in Germany. They believe it possible that this tick might not be able to complete its life cycle on hu man blood.

It is now evident that Porter's (1928) spirited account of "A. persicus in Calama, Antofagasta Province, Chile, must be referred to A. reflexus (or to the American variant; see DISTRIBUTION above), as indicated in the following paragraph. Bites of these ticks were sufficiently numerous and painful for attention to be devoted to the matter in the daily press of the region. Specimens furnished parasitologists as the cause of this "grave molestation" were iden tified as A. persicus. Concerning Porter's report, Kohls (correspond ence) has provided the following note for inclusion here.

"Early in 1950, I received from Dr. Amador Neghme R., Chief Department of Parasitology of the Public Health Service, Chile, four adults and a nymph (said to be) Argas persicus, collected in the Province of Antofagasta at the town of Calama. This seems to be the only Chilean place where this tick occurs, and is found in human houses and in dovecotes. In reply to his letter, I said, "Study of this material indicates that the ticks are not Argas persicus but Argas reflexus, ..... The only South American specimens of reflexus that I have seen previously were collected in chicken coops at Bogota, Colombia..... The Calama specimens appear to agree in all particulars with reflexus of the Old World and from Bogota except for the presence of a few quadrangular plates interspersed with the striae on the flattened margins. This difference could well be due to variation and for this reason I would like to have more specimens from Calama for study". In response to this I received eleven adults from Calama and twenty adults and fifteen nymphs from Chuquicamata, a town about twenty miles away. The source was not mentioned in either case, but all the specimens proved to be the same as those sent previously. In brief, these specimens from Chile that I have seen are not Argas persicus but are probably local variants of A. reflexus

The subject of A. reflexus as a human parasite will be treated more fully in a subsequent volume of this work.

BIOLOGY

The pigeon tick may remain unfed in or near pigeon houses for many months, or even for several years (Nuttall et al 1908. Mayer and Madel 1950). Feeding is much like that of A. persicus, which attacks poultry, and is accomplished at night. Domestic chickens are apparently considerably less liable to attack by A. reflexus than are pigeons. Hiding places of these ticks are easily found in the cracks and crevices of pigeon cotes. The life cycle ap pears to be much like that of A. persicus. Restrictive and optimum biological and climatic factors have not yet been reported in literature. Females feed prior to oviposition, but according to Schulze (1943B), males require only a single blood meal annually.

During the larval stage there is no urinary or fecal excretion (Enigk and Grittner 1952). Nymphs and adults immediately after feeding discharge a mixture of urine and feces, followed by further excretion the following day. The simultaneous deposition of urine and feces causes the rapid formation of a "guanocrystal" in the viscous mass, thus frequently leaving a white center of urine sur_ rounded by a dark fecal ring on the surfaces on which the substance has been deposited. (Note: Compare this type of excretion with that of Ornithodoros moubata). Adults deposit only urine for some two weeks after feeding, then at long intervals a mixture of feces and urine. Four weeks after feeding, females begin oviposition, during which time no excretion is seen. Coxal fluid is seldom voided during feeding, but usually begins only following complete engorgement (Zuelzer 1920B, and our own observations).

DISEASE RELATIONS

MAN: Human beings who venture near occupied or long abandoned pigeon houses are readily attacked, and the ticks may invade nearby human habitations after pigeons have left their usual resting places. Pain or irritation may be felt for years after the pigeon argas has bitten. This species is incapable of transmitting spirochetes of African tick-borne relapsing fever (Borrelia duttonii).

PIGEONS: Squabs are especially susceptible to bites of this tick and adults too may suffer to the point of death by exsanguina tion when their houses are heavily infested. The pigeon argas is of negligible importance in the transmission of Salmonella bacteria among pigeons but does transmit fowl spirochetosis, B. anserina (= B. gallinarum). It is said to be probably capable of transmitting fowl piroplasmosis (Aegyptianella pullorum).

MISCELLANEOUS: In Egypt, the pigeon argas is infected with one or more viruses distinct from West Nile but otherwise uniden tified.

REMARKS

Egypt is the only territory on continental Africa where the pigeon tick is known to be of some economic importance. The review of this species for the present work has not been as inten sive as for most other species.

The temperature preferences of unfed and engorged pigeon argas have been described by Herter (1942).

The anatomy has been described by Pagenstecher (1862).

According to Zuelzer (1921), A. persicus and A. reflexus mate and produce fertile offspring. We have unsuccessfully attempted to duplicate this phenomenon in our Cairo laboratories.

With reference to remarks on coxal fluid by Remy (1921,1922B), see 0. moubata section, page 173. See also Lavoipierre and Riek (1955).

Senevet (1920A) discussed the relationship of the size of the pads of the first pair of legs in larvae in relation to overall body size.

Schulze (1943B) figured the midgut, as A. columbarum, to il lustrate his observation that in the argasids, and particularly in this species and in bat-parasitizing species, there is little basal branching of the diverticula but considerable distal branching.

Schulze (1941) also noted and illustrated the haller's organ of each stage of the pigeon argas. K. W. Neumann (1942), a student of Schulze, discussed the morphology and function of the dorsal plate of the larva, also under the name A. columbarum.

There is some chance that the name A. reflexus refers to a European parasite of wild birds and the correct name of the pigeon parasite should be A. columbae (Hermann, 1804) (cf. DuBuysson 1924).