In Nuttall's laboratory experiments, larvae fed on dogs and rabbits, nymphs on dogs, jackals, and hedgehogs, and adults on dogs and jackals. Larvae commenced feeding three to seven days after emergence, nymphs began about the same length of time after molting, and adults about a week after molting. Larvae fed for three to eight days (mostly four days) (temperature ranged from 6.5°C. to 20°C.). Nymphs fed for three to eleven days (mostly four days), on the dog or jackal; but when hedgehogs were used, the feeding time (ten to seventeen days) was about doubled* (temperature ranged from 8°C. to 18°C.). Females fed from one to three weeks (mostly eight days) but males remained attached indefinitely and transferred to another host if the first animal died. As already stated, the length of intervals during which ticks are off the host appears to be influenced by temperature (though more exact and extensive research is certainly required). In Nuttall's tests, eggs hatched in from seventeen to nineteen days at 30°C. but required 75 days at 12°C. Larvae molted to nymphs from five to eight days after completing feeding (at 30°C.), and nymphs molted to adults in eleven or twelve days after feeding (at 30°C.). Oviposition commenced three to six days (average three or four days) after females left the host, when maintained at 30°C.; but at 12°C. they commenced oviposition after 25 days. Egglaying lasted for from nine to fifteen days. The life cycle, under favorable conditions, may be completed in as little as 63 days. Under unfavorable conditions, it may be prolonged for many months. By way of contrast to Nuttall's findings and because the records of Christophers (1907) "are not complete and do not indicate the temperature at which the specimens were reared" Sapre (1945) undertook similar experiments in India at 7500 feet altitude, with dogs said to be the hosts for all stages. Nonfeeding ticks were observed at 22°C. (eight degrees lower *A similar situation has been reported for Ornithodoros arenicolous whose females feed on mice for 45 minutes but on hedgehogs for 70 minutes (average), and whose males feed on mice for 45 minutes and on hedgehogs for 57 minutes (average) (Hoogstraal 1953C). R.H. than the temperature in Nuttall's experiments) and at 80% to 90% Unfortunately for purposes of comparison, Sapre neglected to report how soon after hatching larvae commenced feeding and other such details. In his summary, Sapre stated that feeding periods remain constant irrespective of temperature variation but nonfeeding periods appear to be inversely proportional to an increase or decrease in temperature. In the introduction it was stated that nonfeeding ticks were observed at 22°C. and the report of the experiment shows no comparative data for length of feeding time at different temperatures. The summary stated all stages were observed at 22°C.; the text stated hosts were maintained at anywhere from 1.4°C. to 11.6°C. for larval feeding, at 2.9°C. to 5.1°C. for nymphal feeding, and at 11.0°c. to 14.6°C. for adult feeding.7 Survival of unfed larvae may be as long as 253 days; nymphs appear to be less hardy, for only a few survived for as long as 97 days. Adults may live without food for as long as 568 days, with females appearing to survive longer than males when unfed. Nuttall Nuttall noted that females may outnumber males by two to one and Sapre reported the sex ratio as three females to two males. Copulation occurs on the host; males may move about on the host and fertilize several females. Nuttall counted 1400 eggs to 3900 eggs from individual fe males (Sapre said his females averaged 2140 eggs). Lombardini (1950) counted from 4000 to almost 5000 eggs. Regendanz and Reichenow observed that the number of eggs varies with the size of the female but averages from 3000 to 4000. However, not all eggs are deposited. When the female at last becomes exhausted and senile, some mature eggs remain in the oviducts and egg cells remain in the ovaries. A good egg batch, from an engorged fe male measuring from 8.0 mm. to 9.5 mm. long, weighs from 0.09 to 0.1 gram. A classical study on oviposition and survival of eggs and larvae under certain conditions has been reported by Lombardini (1950). Five females laid from 4000 to almost 5000 eggs each, ovipositing for from 21 to 29 days each. The number of eggs laid in the latter half of the period dropped considerably, though erratically, from week to week. The mechanism of oviposition in the kennel tick is similar to that reported by Nuttall and Warburton (1915) for Haemaphysalis punctata. The cephalic gland, or gene's organ, secretes a liquid covering as each egg is emitted. This substance protects the eggs from dessication but absorbs oxygen, even under water. Immersed eggs hatched in 51 days as compared to 38 days in the air (20°C. to 25°C.), although some embryos were killed by a Fusarium fungus. Even larvae survived from 30 to 35 days in spring water, while others, unfed, succumbed in twelve days in moist petri dishes. Larval longivity when immersed in various fluids was also noted. Illustrated with handsome photographs of the egg covering, various glands and organs, the Fusarium which attacked eggs, and details of the larval external structure including integumentary sense organs, this paper should be studied by anyone seriously interested in tick biology. Other laboratory hosts reported by various workers have been hamsters for the larval and nymphal stages (Malamos 1938). Larvae detached engorged in six days from hamsters. Nieschulz and WawoRoentoe (1930) used guineapigs for feeding all stages of the tick; mice were also used for larval feeding, although guineapigs were preferred. Feeding time was stated to be 24 hours for larvae and two or three days for nymphs. Dogs were preferred for adult feeding. These experiments, undertaken at 26°C. to 27°C. and at ordinary (high) humidity (of the Netherlands), are notable for the rapid feeding of the immature stages (ticks originated from Java). In contrast, Blanc and Camino petros (1931), when using ground squirrels, or spermophiles, Citellus citellus, in Athens, noted larval feeding times of five to eight days. Korshunova and Petrova Piontkovskaya (1949) fed all stages on guineapigs in their studies of boutonneuse fever in the Crimea. Blanc and Bruneau (1948) used guineapigs for feeding immature stages and a hedgehog as adult stage host. A brief abstract of rearing results using white rats and guineapigs for larval hosts and dogs for nymphal and adult hosts has been presented by Luttermoser (1947). Ecology In the preceding section on biology of the kennel tick the number of queries raised suggest how much information is lacking on the ecology of this parasite. In Egypt it is certain that there is an urban race, attacking dogs almost without exception, and a field race that parasitizes rodents, hedgehogs, håres, and, when available, domestic animals. The field race occurs only on the Mediterranean littoral, rarely in scattered desert areas and oases, and in conjunction with a few rodents of cultivated areas. The domestic race is common in urban and settled areas; along with hyalommas it is almost the only ixodid ever found in those desert areas that support some grazing. However, the propensity of the domestic race for seeking out favorable niches of human habitations and domestic animals, which are always sheltered from thieves and from pedators in these areas, causes it to be more localized than are its ubiqui tous field companions, such as H. excavatum. The actual relations of urban and field races we hope to determine as early as possible. In tropical and southern Africa, it appears that R. s. sangui neus is generally distributed through the warm and humid zones of the continent. In the more arid parts of this area, its presence or absence seems to be dependent largely on human cultural patterns, especially of pastoral tribes (see Cattle Hosts, page 698). Whether urban and field races exist in Africa south of the northern deserts is at present difficult to determine from available data. Most observations on host parasite relations presented below apply to domestic populations. Larvae attach to the host mostly in hairy places but may occur anywhere on the body. Nymphs are found indiscriminately among the fur or elsewhere. Adults are especially common on and in the ears, though they may attach along the nape, between the toes, or anywhere else. Specimens on birds are usually found on the crown or about the ears, eyes, or bill. Females often creep upward on walls after leaving the host and may hide tightly wedged in narrow cracks as high as fifteen feet above the ground (Christophers 19070). Eggs are deposited, either near the ground or high above it, in crevices in woodwork, under plaster, whitewash, or paper, or, out-of-doors, under stones (Lewis 1934, Roberts 1935, du Toit 1947). Tremendous infestations frequently occur. In Cairo, one may see houses "crawling with" kennel ticks and mongrel dogs with more ticks than hairs on them. Heavily infested houses are common elsewhere and are frequently noted in literature from the United States. The rapid spread of this pest, once introduced to a new island or major geographical area, is also the subject of numerous reports. Sometimes, however, its paucity and relatively slow pace of spread in apparently favorable areas, as, for instance, Mada gascar, is noted (Hoogstraal 1953E). In the United States, since first reported from Texas and New Mexico (Banks 1908 as R. texanus), R. s. sanguineus has spread widely (Bishopp and Trembly 1945, Kohls and Parker 1948) through much of the country. It now occurs in some areas where winters are severe but its spread northward ap pears to be much slower than in warmer states. In those parts of the world where definite seasonal changes occur, a spring peak of abundance is commonly observed. During summer and fall, populations, even though great, are not so frequently noticed, probably because they are more scattered in minor peaks of abundance resulting from rapidity or delay with which ticks find hosts. As one example, dogs at Rabat, Morocco, which has seasonal and climatic conditions roughly similar to those of the southern United States, were observed to be very lightly parasitized during the months of December through Feb ruary (Gaud and Nain 1935). In March, the number of ticks began to increase, and in April and May nymphs made their appearance. In May, the count was highest (33 ticks per dog, average), but the infestation rate remained high through August. A sharp decline in numbers was noted in September, followed, inexplicably, by an October rise. Among the 9000 ticks collected, the ratio of males to females was two to one. In order to obtain a more accurate picture of seasonal incidence and abundance in relation to the tick's life cycle, presumably it would be advisable to dis regard the long-feeding males and count only larvae, nymphs, and females (HH).7 In Algeria, adults appear suddenly in large numbers on domestic animals at the end of April and may be found till August, with the maximum numbers in May. Adults are rare or absent in autumn, winter, and early in spring. Nymphs are found on domestic animals in spring (Sergent and Poncet 1937,1940). This last ob |