2 STUDIES IN INSECT LIFE, ETC. 



substantially diminish that food supply, and by 

 leaving their larvae behind in the diminished 

 stock render the food unpalatable ; and (b) those 

 which infect the food supply with pathogenic 

 germs, such as the germs of enteric fever. 



Amongst the insects which bite man, or, rather, 

 pierce his skin, and which in times of peace can 

 be kept in some sort of control, is the louse. In 

 times of war, when men are herded together, 

 with little or no opportunity of changing their 

 linen or washing, the louse is sure to appear 

 and it spreads rapidly. 



We will confine our attention to the genus 

 Pediculus P. capitis, the head-louse, and P. 

 vestimenti, the body-louse. They do not arise, 

 as the uninformed think, from dirt, though they 

 flourish best in dirty surroundings. No speci- 

 men of P. vestimenti exists which is not the direct 

 product of an egg laid by a mother-louse and 

 fertilised by a father-louse. In considerable col- 

 lections of men drawn from the poorer classes, 

 some unhappy being or other often through no 

 fault of his own will turn up in the community 

 with lice on him, and these swiftly spread to 

 others. 



Like almost all animals lower than the mam- 



