[47] Adaptation of Ticks 325 



warmth from proximity to animals upon which they feed. Thus, 

 Argas reflexus and Argas vespertilionis, which occur in colder climates, 

 are parasitic on pigeons and bats respectively, and they obtain shelter 

 in pigeon coops and the retreats of bats. 



Like all other ticks, they pass through larval and nymphal stages 

 before attaining maturity. In some Argasidae the larvae suck blood 

 (as in Ixodidae); in others they do not. Where the larvae suck blood 

 they remain attached to the host for 5-10 days or more (as in Ixodidae). 

 There are two or more nymphal stages in Argasidae (one only in Ixodidae), 

 and the nymphs, with one exception, Omithodorus megnini, are rapid 

 feeders, that is, they usually feed on blood to repletion within 20-30 

 minutes (the nymphs of Ixodidae take several days to become gorged). 

 The adults are not only rapid feeders, but they may feed repeatedly 

 (not so in !j! Ixodidae, though possibly in Js). 



The nymphs 1 and adults of Argasidae are rarely carried away from 

 the habitats by their hosts because they feed rapidly. They are mostly 

 nocturnal feeders, attacking the host when the latter is sleeping or resting. 

 All species of Argasidae would appear to shun the light, especially when 

 waiting for a host. When hungry they may leave their hiding places 

 during the daytime if they become aware of the proximity of a host. 

 The Argasidae infest the habitat of the host. 



The nymphs and adults of Ixodidae behave in a very different 

 manner. The nymphs attach themselves to the host, and are carried 

 about for several days, and possibly longer. This likewise holds for the 

 adults of both sexes in a large number of species. The duration of 

 their parasitism upon the host may be much prolonged, especially 

 when the host is a cold-blooded animal ; thus, species of Amblyomma, 

 Aponomma and Hyalomma, occurring on Reptilia, may remain attached 

 to the host for many months. On the other hand, we shall see that 

 there are species of Ixodes in which the males are unknown or in 

 which they are only recorded as having been found in the habitats 

 of their hosts. 



In the Argasidae the females lay eggs in batches after successive 

 feeds, and the total number of eggs laid by a female is comparatively 

 small, say 200. In the Ixodidae, the eggs may number one or more 

 thousands. The explanation of this difference in the number of eggs 

 laid appears obvious when we consider the life habits of the two 

 families. The Argasidae are essentially ticks of the habitat in their 

 nymphal 1 and adult stages; the females lay their eggs in and about 

 1 Omithodorus megnini excepted. 



