THE FLEAS 



3037 



THE FLEAS Family PULICID^, etc. 



The fleas, which by some are regarded as an order (Aphaniptera), may be con- 

 sidered to be aberrant flies; their mouth organs, which are adapted for piercing and 

 sucking, being modified upon the same principles as obtain in the flies. They 

 further resemble that group in undergoing a complete metamorphosis, but differ 

 from the majority of flies in being destitute of wings. The group is divisible into 

 two families. In the true fleas or Pulicidiz the body of the adult is strongly flat- 

 tened from side to side, and thus, in conjunction with the smooth, hard, and nearly 

 naked integument, enables the insect to swiftly traverse the hairy coating of its 

 host. Some of the segments, however, are usually armed with strong backwardly- 

 projecting spines. There are no compound eyes, but each side of the head is fur- 

 nished with a simple eye; the legs being long, strong, and fitted for leaping. The 

 eggs are laid about the floors of houses, kennels, etc. ; and the larvae, which are 

 slender, worm-like creatures, devoid of legs, but furnished with a biting mouth, 

 live on particles of decaying organic matter found in the dust of the places they in- 

 fest. When adult, the larva, or maggot, is said to spin a cocoon within which the 

 pupa state is passed. In addition to mankind fleas {Pulex} live parasitically upon ' 

 other animals such as dogs, cats, badgers, pigeons, fowls, moles, hedgehogs, squir- 

 rels, etc. They are, moreover, even more abundant in tropical than in temperate 

 countries. Tennent, for instance, says that in Ceylon "they may be seen in 

 myriads in the dust of the streets, or skipping in the sunbeams which fall von the 

 clay floors of the cottages. The dogs to escape them select as their sleeping places 

 spots where a wood fire has been kindled; and here, prone on the white ashes, their 

 stomachs close to the earth, and their hind-legs extended behind, they repose in 

 comparative coolness, and bid defiance to their persecutors." 



To the family Sarcopsyllidce be- 

 longs the dreaded chigoe or jigger 

 {Sarcopsyllus penetrans\ of tropical 

 countries. The adult female bur- 

 rows beneath the skin of the foot, 

 and shortly after effecting an en- 

 trance her body becomes swollen up 

 with eggs, and grows to the size of a 

 pea. At this stage she may be easily 

 extracted, and as the young are not 

 parasitic it is seldom that serious re- 

 sults ensue. According to Mr. W. 

 H. Blandford, "the recorded distri- 

 bution of the chigoe extends over 

 tropical America and the Antilles, 

 from 30 N. to 30 S. , and in late 



years it has been exported in ballast to Africa, and has established itself in Angola, 

 I^oango, and the Congo." It also occurs in British Central Africa, where quite 



COMMON FLEA AND ITS STRUCTURE. 



Egg; 2. I,arvse; 3. Pupa; 4. Perfect insect; a. I,abrum; 

 b. I,abium; c. I,abial palpi; d. Mandible; e. Maxil- 

 lary palpi. 



