HOUSEHOLD AND CAMP INSECTS 4I 



order of their importance, the fork of the trousers and the arm 

 pits, the triangles at the tail of the shirt; next are the trousers 

 and shirt seams, and then the neck. Eggs have even been found on 

 the beads of rosaries. The insects accumulate where there is 

 warmth, humidity and shelter. 



These parasites may survive separation from the human body for 

 a period of 9 days. They may penetrate dry sand or earth to a 

 depth of 12 inches and live beneath it for 4 days.^ 



The base trenches are somewhat less infested than dugouts, 

 though troops suffer about equally in both owing to the impossi- 

 bility of changing underclothes in the former. Blankets are con- 

 sidered as minor factors, though straw may protect living insects for 

 a period of 7 days, and thus be a source of infestation.*' 



Body lice may be blown from partly stripped men for several 

 feet and perhaps farther.'^ When at a greater distance than 15 to 18 

 inches from the skin, they wander about aimlessly, although when 

 not feeding the lice attach themselves to fragments of clothmg, 

 which is very probably the explanation of typhus infection among 

 doctors.^ Underfed or cold lice do not oviposit. The eggs are 

 probably not laid on straw bedding under natural conditions, since 

 Ggg laying ceases at 76° F., and a daily fall of temperature to 61° F., 

 even though it lasted for 2 hours only, caused a considerable reduc- 

 tion in the number of eggs. It is probable that hatching and ovi- 

 position would stop if at night all clothes were removed and placed 

 where the temperature were 61° F. or lower, and the bedding was 

 left during the day in an unheated place. ^ 



Lice are able to Hve without food for 2 to 5 days at a temperature 

 of 85° F. in moist air, and from 2 to 3 days in dry air. At 68° F. 

 they live from 3 to 6 days in moist air and from 2 to 4 days in dry 

 air, while at 60° F. they live respectively 4 to 6 and 4 to 5 days.^° 

 The louse becomes rigid with cold at 10° F., but revives when the 

 temperature rises. Dry heat at 104° F. will kill a gorged louse in 

 6 hours, or a hungry one in 2 hours.^^ Dry heat about 129° F. 

 causes death after one-half to three-quarters of an hour.^^ 



■^ Hase. Rev. Appl. Ent., 5 144. 1917. 



^' Brit. Med. Jour., no. 2891, p. 746. 1916. 



7 Schilling, Munchener Med. Wochenschr., 63:1176. 1916. 



^ Swellingrebel, Rev. Appl. Ent., 5 :3.V34- I9i7- 



» Sikora, Centralblat. f. Bakt. Parasit. u. In'fektionskrankheiten, 76:523-37- 



10 Englehard. Rev. Appl. Ent., 4:50. 1916. 



^1 Zucker, Centralbl. f. Bakt. Parasit. u. Tnfektionskrankheiten, 76:294-307. 



1915- 

 1- Bacot, Brit. Med. Jour., Ja. 29, '16. 



