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 1.9U5 , Kohls 

 and Parker 19^3^ through much of the countjry. It now occurs in 

 some areas where winters are severe but its spread northward ajp- 

 pears to be much slower than in warmer states. 



In those parts of the world where definite seasonal changes 

 occiiT, 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 abundaince res\ilting 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 Main 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 ac- 

 curate 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 do- 

 mestic 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 1937,19^0). This last ob- 



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