356 The Two-winged Flies 



horse, cow, sheep, etc., as well as birds. The male jigger-fleas hop on or 

 off the host as other fleas do, but the females, when ready to lay eggs, burrow 

 into the skin, especially that of the feet, and produce a swelling and later 

 a distinct ulcer, sometimes so serious as to result fatally. The remedy is 

 (as also for the chigger-mite) the pricking out entire, with a needle or knife- 

 point, of the pest as soon as its presence is detected. The bursting of the 

 body of the female in the skin, with the release of its eggs, is likely to result 

 seriously. When domestic animals are attacked it is difficult to fight the 

 pest. The liberal use of pyrethrum on the rubbish or dust in which the 

 young stages are developing is recommended. The hen-flea, Xestopsylla gal- 

 linacea, first described from Ceylon, sometimes becomes a serious pest of 

 fowls in warm regions. The females of the hen-flea burrow into the skin of 

 the fowl and lay their eggs in the small tumor which forms about them. 

 This pest has been known in the Southern United States since about 1890 

 and is a common pest from Florida to Texas. 



, The second family, Pulicidae, includes all the other fleas, none of which 

 burrows into the skin. The various species range in size from ^ inch (Anomi- 

 opsyllus nudatus, found on a mouse in Arizona) to inch (Ceratophyllus 

 stylosus, taken from Haplodon in Oregon), but all fairly similar in shape 

 and appearance to the familiar house-fleas. They are grouped in nine 

 genera, of which Pulex is much the largest and mcludes the human flea 

 and the cat- and dog-flea, the two species to which the house-infesting pests 

 belong. The human flea, Pulex irritans, was described by Linnaeus in 

 1746. It is known all over the world, and often becomes a serious pest. 

 In this country it is probably not so commonly met with in houses as the 

 cat- and dog-flea, Ctenocephalus canis, from which it may be readily dis- 

 tinguished by its lack of combs of spines on the back of the head and 

 prothorax. The eggs of irritans "are deposited in out-of-the-way places, 

 in the dust or lint under carpets, and the larvae are said to feed upon the 

 particles of organic matter which may be found in such localities." Raillet 

 states that each female deposits eight to twelve eggs from which larvae hatch, 

 in summer, in from four to six days, become pupae eleven days later, and 

 after about twelve days in this stage become adult. In winter, in warmed 

 houses, the whole development takes about six weeks. The cat- and dog- 

 flea lays its eggs on or among the hairs of an infested animal, but the 

 eggs drop to the floor or ground as the animal moves about, and the larvre 

 live in the dust, feeding on whatever bits of organic substance they can find 

 there. Larvae placed on dust with birds' feathers mixed with dried blood 

 developed perfectly. Others put on the sweepings of a room developed 

 as well. These fleas are especially abundant and troublesome in houses 

 in the East in damp summers. As flea-larvae will not develop successfully 

 in places where they are often disturbed, much sweeping and scrubbing 



