28 MEDICAL ENTOMOLOGY 



EXERCISE 16b 



THE FLEAS 



ORDER SIPHONAPTERA 



Systematic Study. 



Order Siphonaptera wingless insects, laterally compressed, 

 body highly chitinized, provided with many regularly arranged 

 spine-like hairs. 



A. Family Sarcopsyllidae, "Small fleas with disproportion- 

 ately large heads; female a stationary parasite with worm-like 

 or spherical abdomen, burrowing into the flesh of the host; labial 

 palpi one-segmented; no * combs' of spines on head, thorax or 

 abdomen" (Kellogg). 



a. Examples, Sarcopsylla penetrans, the jigger-flea or chigoe 

 of mammals, including man. 



b. Xestopsylla gallina, the hen flea. 



B. Family Pulicidae, "larger fleas with proportionately small 

 head; adults active temporary parasites, with abdomen always 

 compressed; labial palpi 3 to 5 segmented; head, thorax or 

 abdomen often with 'combs' of spines" (Kellogg). 



a. Examples, Pulex irritans, the human flea, non-combed. 



b. Ctenocephalus canis, the dog and cat flea, two sets of 

 combs, one oral and one thoracic. 



c. Ceratophyllus fasciatus, the rat flea, thoracic comb present, 

 but oral comb absent. 



d. Ceralophyllus acutus, the squirrel flea, thoracic comb 

 present, consisting of nine spines on one side. 



Draw the hen flea and either the rat flea or the squirrel flea. 



