554 MEDICAL ENTOMOLOGY 



does not thrive apart from its host. Warburton found that the lice on 



verminous clothing were usually dead when they reached 

 Bionomics . 



his laboratory, and that they could not be kept alive 



even when placed in an incubator at a steady body temperature. In a 

 few cases he found specimens able to survive as much as four days 

 starvation, but this was very exceptional. The authors have had similar 

 experiences in the cold weather in Madras, having found that lice taken 

 from the human subject in the early morning and placed on pieces of 

 cloth, in carefully cleaned and dried tubes, were generally dead in the 

 afternoon. In carrying out the breeding experiment detailed above, 

 however, no such difficulty was met with, and the lice were bred from the 

 egg to maturity without any special precautions being taken, and were 

 kept, from the time they hatched from the egg, in tubes on the laboratory 

 table. It has not been ascertained whether it is the comparatively small 

 increase in the temperature, which would not amount to more than ten 

 or fifteen degrees, which makes the difference, or whether it is that the 

 immature stages of lice are more hardy than the adults. Warburton 

 found that newly hatched lice die in 36 hours if not fed ; the present 

 writers have found them alive up to two days, a longer period than the 

 adults will usually survive. 



The eggs of lice, on the other hand, appear to be able to resist 

 unfavourable conditions to a much greater extent. According to 

 Warburton they may take as long as a month to hatch, a most important 

 fact in considering the possibility of spread by infected clothing, etc. 



The rearing of lice in captivity is a difficult and troublesome task, as 

 will be readily understood from what has been said with reference to 



Breeding Technia e tne ^ r susceptibility to unfavourable conditions. The 

 difficulty appears to be greater in a cold climate than 

 in hot one. Warburton, who carried out his experiments at a time when 

 the room temperature on some occasions fell considerably below freezing 

 point, succeeded in keeping them alive for over a month and rearing them 

 from the egg by the following method. A female was placed in a glass 

 tube about 3 ins. by '5 in., together with a piece of cloth on which to 

 rest, and with a male. The tube was then plugged with cotton wool and 

 enclosed in a metal case open at one end, to guard against accidents, and 

 carried close to the person night and day, the lice being fed twice a day. 



The eggs when laid were allowed to remain on the cloth, as it was found 

 that no matter how carefully they are handled they die if any attempt is 

 made to remove them. The adults are easy to feed, as they remain 

 clinging to the cloth, but the larvae give trouble on account of their 



