1. Biting lice ( Mallophaga)

Kloet & Hincks (1964) list 514 species and just over 40 of those were recorded by Dr. F.A. Turk in the 1940s and early 1950s in Cornwall, since when there seems to have been no further work. All are external parasites of birds and mammals feeding on hair, feathers and sometimes blood; they die within a few hours of leaving the host on which their status of “rare” or “common” mainly depends (Tilling, 1987). Most are host-specific as is reflected in the scientific names of some e.g. the louse of Upupa epops is Upupicola upupae (Schrank). Unexpected relationships of some groups of birds have been discovered by examining their biting lice which have evolved with them.

2. Sucking lice ( Anoplura)

25 species in five genera are listed by Kloet & Hincks (1964). All are external parasites and 12 have been recorded on the various domestic and wild mammal hosts in Cornwall and the Isles of Scilly - including the Grey Seal - by Dr. F.A. Turk in the 1940s and 1950s. Of the two species of human lice, the Head Louse Pediculus humanus Linnaeus (which also lives on the body and can remain in clothing) seems to be cyclical according to Dr. Mark Hewitt (pers. comm.) who said it became markedly more common in 1974. According to The West Briton it was increasing again in 1989. There is a theory that a general increase started in the late 1970s when cooler washes with enzyme powders rather than boiling was instigated. By contrast the Pubic Louse Phthiris pubis (Linnaeus) has become very uncommon. No sucking lice were listed by earlier naturalists, and none are listed by Prof. James Clark in Page (1906).