Gr. H. F. Nuttall 
47 
Avarmth from proximity to animals upon which they feed. Thus, 
Argas reflexus and A7-gas vespei'tilionis, 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 moi’e (as in Ixodidae). 
There are two or more nymphal stages in Argasidae (one only in Ixodidae), 
and the nymphs, with one exception, Ornithodorus 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 $ Ixodidae, though possibly in (/s). 
The nymphs^ 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 and adult stages; the females lay their eggs in and about 
1 Ornithodorus megnini excepted. ^ 0. megnini excepted. 
