ENTOMOLOGY

8041 SANITARY ENTOMOLOGYstereotyped account of the life history, on the assumption that this articlewill be read by all those interested.The first point to be noted is the fact that body lice may oecur onthe body as well as on the clothing. Nuttall has brought out convincingevidence that nits as well as lice themselves are often found upon the bodyhairs, especially in the axillae, the hairs of the breast, and at times on thepubic hairs and even the hairs of the thigh and leg. We have Seen twocases in which both lice an«:l nits were present in the axillae. The importanceof this point as regards control measures is obvious. Disinfectionof the clothing is not sufficient, but must be accompanied by a thoroughbath with some insecticidal liquid, such as cresol-soap, or the kerosenesoap used by Boyd in his work with the Mexican laborers of the Sante FeRailroad.Moreover, it was soon discovered from actual experience in this warthat a disinfection of a part of the clothing was entirely ineffective; forexample, if clean shirts are provided, while the trousers have not beencleaned, lice quickly migrate from the trousers to the clean shirt whichaffords them new areas for deposition. Thus conditions are soon as badas before. .A second point having an important bearing on control measuresis the number of eggs laid per female and their rate of development. Theimportance of the improved technique for rearing lice, mentioned above,consists in showing that previous statements, regarding the number ofeggs laid, elearly underestimated their power of reproduct.ion. 'Vhen thelice are fed but twice a day only four to five or six eggs are obtained perday, while by the wristlet method Nuttall obtainl!d as high as twelve eggsper day per female, the average being about ten. He states that corporismay lay !75 to 800 eggs during its lifetime. By the same methodthe senior writer has obtained as high as fourteen eggs per day, with anaverage of about eleven per day over a period of twenty-five days.'l'he eggs are elongate, oboval, with a granulated cap or operculumat the outer end (plate XXII). They are cemented singly to a hair (inall three species), or a thread (P. corporis). Occasionally a single hairwill be covered with them. Oviposition usl1ally commences in P. corporiswithin two days after maturing.\Vhen a female is ready to oviposit she clings to a hair or thread,and slipping backward, grasps it also with the gonopods and the posteriorlobes of the last segment. A drop of cement is excreted, followedby the egg, which is thus firmly cemented to the hair and the insectmoves away. Thc entire operation consumes about 17 seconds. Theoperculum is usually directed away from the root of the hair.Oviposition takes place most readily at about 30 0 C. (86 0 F.) andceases at !OO C. (68 0 F.). They lay rll:pidly at 37 0 C. (99 0 F.) although