Carl Linnaeus, The Lapland Journey, translated by Peter Graves (Edinburgh: Lockharton Press, 1995), p. 143.

Jokkmokk [2], 19/07/1732, ¶745:

The Lapp lets lice freeze to death in the winter and, since he does not have a brush, knocks them off with a switch after they have turned red. They turn red when they are frozen. In summer he kills them with his nails after putting his clothes in the sun so that the lice crawl out of them.