1 68 



ECONOMIC ENTOMOLOGY 



^ Pediculid^ 



(Consult Bull, s, Div. Ent., U. S. Dept. Agr.; Bull. 48, Minn. Agr. Exp. St.) 



Most domestic animals at some time or other are liable to become 

 infested with sucking lice which cause considerable irritation. The 

 eggs or "nits" are attached to the hairs, and the lice by means of a 

 beak suck the blood of their victims. 



Treatment consists in the application of tobacco water or Black 



Leaf 40 ( I part to 1000 water), dilute carbolic acid, kerosene emulsion, 



sulphur and mercuric ointment, or an infusion of 4 



oz. stavesacre and i oz. hellebore, or creolin solution. 



Two genera are of importance economically — 



y^c^^'^HiiHt^ P'^diculiis occurring on man, and Hcematopinus on 



V _r;:^^w»^ ^ domestic animals. 



Head-louse of Man {Pediculus capitis De Geer). 

 — Whitish with faint dark markings on sides. Eggs 

 (50) glued to hairs, whitish, hatch in 6 days and 

 young become mature in about 3 weeks (Fig. 108). 

 Body-louse of Man {Pediculus vestimenti Leach) . 

 — Similar in shape to preceding, but larger and at 

 maturity with upper surface transversely banded 

 with black. Eggs laid in the folds in clothing. 

 Bacot {Parasitology, 191 7) states that P. capitis and 

 P. vestimenti may cross-pair with fertile offspring. 

 He found that the average number of eggs per day 

 was 3.7 for capitis and 6.4 for vestimenti. The egg period for the 

 latter was estimated at 12 days, and 12 days more for the maturity 

 of the female. "Allowing an average of 8 eggs per day, spread 

 over a fertile period of 40 days we find that during her life a single 

 female may have 4160 offspring." A carrier of typhus fever. A 

 common pest of army camps. 



Control Measures. — Change clothing as often as possible; wash 

 infested clothing with a cresol soap made as follows: water 10 gal., 



Fig. 108.— 

 Head louse {Pedi- 

 culus capitis). En.' 

 larged. 



Jeyes' Fluid 



H oz. 



soft soap 1^2 ''^-5 bathe body using cresol soap; 



place N.C.I, powder in shirt and trousers (naphthaline 96 per cent., 

 creosote 2 per cent., iodoform 2 per cent.). 



Crab-louse of Man {Pediculus pubis = Plithirius inguinalis Leach) . 

 — Body as wide as long, with strong legs. Eggs glued to hairs. Mouth- 



