Gr. H. F. Nuttall 
427 
Drying and Storage of Clothing and Effects as a Means of 
Louse Disposal. 
In the section on Biology of Pediculus full details are given regard¬ 
ing (1) the longevity of the active stages when starved (pp. 164-169) 
and (2) the hatching of nits under different conditions of temperature 
(pp. 143-147). The information quoted shows that the active stages live 
10 days, at longest, when unfed, and that hatching does not occur at a 
temperature of 22° C. or below. The longest hatching periods recorded 
are 16 days at 25° C. in a dry atmosphere, and 23 days in a damp 
atmosphere at 24-5° C. In a dry atmosphere, the temperature being con¬ 
stant, the longest hatching periods observed were 14 days at 30° C., 
7-8 days at 32-35° C. and 7 days at 37° C. When nits were exposed 
alternately for periods of 12-24 hrs. to cold and warmth, hatching 
could be delayed, in extreme cases, for 35 days, but such alternating 
conditions need not concern us in relation to the storage of verminous 
effects where a more uniform temperature will be maintained, usually 
below that (22° C.) which permits of the development and hatching of 
the egg. Under ordinary conditions, at a temperature of 12-20° C., dry 
storage for 2-3 weeks should suffice in practice to dispose of the nits which 
are considerably more resistant than the active stages. The nits usually 
commence to shrivel up in a few days when kept dry but it is best in 
practice to prolong the storage period. 
This conclusion regarding the requisite storage period is in agreement 
with that arrived at by other observers. Stevenson (1905) in the case of 
the hog-louse recommends that infested pens should be left vacant for 
2 weeks so that the therein contained lice may die. This recommendation 
is evidently based on actual experience, and it accords closely with what 
appears to have been observed in practice with the human body-louse. 
Thus Busson (1915, p. 674) recommends that “infested quarters” shall 
be disused for 2 weeks, Ragg (1915, p. 172) that clothing be stored 2 
weeks, but neither author mentions at what temperature. Heymann 
(hi. 1915, p. 254) in one paper recommends the storage of clothes for 
2 weeks “in tightly closing boxes” (no reason given), whilst in another 
paper (vm. 1915, p. 318) he advises 3 weeks’ storage, at room-temperature. 
The drier the atmosphere the shorter will be the period of storage 
required. A storage room heated by a stove or radiators, during the 
winter months especially, and provided with adequate ventilation would 
doubtless destroy nits and lice within a week. To ensure rapid desicca¬ 
tion the clothing, blankets, etc., should not be stacked in bundles, but 
Parasitology x 28 
