Anoplura 297 



to 45 with the arm. As the feeding progresses the body is gradually 

 lowered, until it rests on the arm. Blood is seen passing into the ali- 

 mentary canal in which a continuous peristalsis is evident. Feeding is 

 continued until all feces and a drop of fresh blood have been ejected from 

 the canal. The average length of a meal is from 8 to 12 minutes, but it 

 may last from 20 to 30 minutes. At its close the mouthparts are with- 

 drawn, apparently by a short jerk of the head. The lice should then 

 be carefully removed from the arm with a small forceps and returned to 

 their vial. They should be held by the legs and not by the body in order 

 to avoid rupturing the distended alimentary canal. Newly hatched 

 lice will feed readily and must be given at least four opportunities to 

 feed in 24 hours until they reach maturity. Mature lice should be given 

 two, and if possible three, opportunities to feed in 24 hours, since those 

 exhausted by too long fasting will not feed on man. 



The unfed louse is of a grayish color and much wrinkled, while the 

 fed louse has a highly refractive, smooth tegument, showing very clearly 

 the areas of sclerotization. 



At every feeding the threads and bristles from each vial should be 

 examined carefully for eggs. These, if present, are found attached to a 

 thread or bristle which should be removed to a second vial. If worn 

 continuously at body temperature and if fertile, the eggs will hatch in 

 13 to 15 days. In the course of their development hog lice undergo 

 three molts. Rearing in captivity has proved the cycle from egg to egg 

 to occupy from 29 to 33 days. The life history, as we have observed it, 

 may be summarized as follows: 



Time from laying to hatching of eggs 13 to 15 days 



First molt occurred after 5 to 6 days 



Second molt occurred after 4 days 



Third molt occurred after 4 to 5 days 



Sexual maturity occurred after 3 days 



Time of development from first stage larva to 



mature adult 16 to 18 days 



Temperature 35 C-> 



(continually next to body in vials) 



Number of feedings in 24 hours. 1 to 4 



Duration of cycle from egg to egg 29 to 33 days 



This method of keeping lice in captivity has proved satisfactory in 

 investigations carried over a period of years, and large numbers of lice 

 have been fed on the forearm without any harmful results. Egg-laying 

 and molting have been observed and lice have been reared from the egg 

 to maturity. All our attempts to rear a second generation of captive lice 

 have failed. Eggs laid by reared females, kept in separate vials with 

 males, have all quickly changed color and become shriveled, although 

 the insects were seen in position for copulation a number of times. 



