THE COMMON FLEA 255 



overlapping parts of the first two abdominal segments. 

 They are, apparently, rudimentary wings. 



Fleas sometimes exist gregariously on their hosts, and 

 those of the lower animals especially have the habit of 

 attaching themselves most pertinaciously to some part 

 of the body, from which no effort of their host can 

 dislodge them. Some years ago, Mr. Yerrall exhibited 

 before the Entomological Society a colony of living fleas 

 which had been taken shortly before from the inside of 

 a rabbit's ear, where they were congregated on a spot 

 from which the animal could not remove them by 

 scratching. The neck of a fowl, again, is another place 

 on which large numbers of a certain species have been 

 found, collected in a small area, with their lancets buried 

 deep in the flesh. They are not slow to discover when 

 their host can furnish them with no further nourish- 

 ment, and it is curious to notice how soon they abandon 

 a dead body. This may easily be observed in the case 

 of the cat's flea : if a recently defunct cat be watched, 

 as the body becomes cold and stiff, the fleas will soon be 

 seen struggling out from amongst the fur, though not a 

 single specimen may ever have been seen as long as 

 the animal was alive and warm, and its blood therefore 

 readily obtainable. 



The human flea is pugnacious, and one observer, who 

 had confined a couple of females in a glass tube, in 

 order to induce them to deposit eggs, describes them 

 as immediately becoming "rampant, confronting one 

 another like microscopic kangaroos." 



Fleas are peculiar amongst parasites as being parasitic 

 only during one stage in their career. It is only the 

 fully grown insects by which we are troubled, and 

 though we find them of different sizes, little ones and 

 big ones, it must not be supposed that the former are 



