524 



APHANIPTERA 



a pair of elongate, slender organs, with serrated edges ; and there 

 is an unpaired, elongate pricking-organ, thought by some to be a 

 hypopharynx, and by others a labrum. The antennae are of 

 unusual form, consisting of two basal joints, and, loosely con- 

 nected therewith, a terminal mass of diverse form and more or 

 less distinctly, though irregularly, segmented. The full number 

 of ten stigmata exists, Wagner giving three thoracic, with seven 

 abdominal, placed on segments 2-8 of the abdo- 

 men ; but Packard thinks the supposed meta- 

 thoracic stigma is really the first abdominal. 

 Fleas undergo a very complete metamorphosis ; 

 the larvae are wormlike, resembling those of 

 Mycetophilid Diptera (Fig. 252). The egg of 

 the cat's flea is deposited among the fur of the 

 animal, but (unlike the eggs of other parasites) 

 apparently is not fastened to the hair, for the 

 eggs fall freely to the ground from infested 

 animals; the young larva when hatched bears 

 on the .head a curious structure for breaking 

 the egg-shell. It has the mouth -parts of a 

 mandibulate Insect and is peripneustic, having 

 ten pairs of stigmata. It subsequently becomes 

 of less elongate form. Flea-larvae are able to 

 nourish themselves on almost any kind of refuse 

 animal matter, Laboulbene having reared them 

 on the sweepings of apartments ; they may 



FIG. 252. Larva of f. ' , , , , 



Pulex serraticeps, perhaps sometimes ieed on blood ; at any rate 

 the dog- and cat- th e contents of the alimentary canal appear red 



flea. (After ' r 



Kiinckei.) through the transparent integuments. When 



full grown the larva makes a cocoon, and 

 frequently covers it with pieces of dust. The perfect flea 

 appears in a week or two thereafter ; the pupa has the members 

 free. The food of the larvae of fleas has been much discussed 

 and a variety of statements made on the subject. It has been 

 stated that the mother-flea after being gorged with blood carries 

 some of it to the young, but Kiinckei has shown that there is 

 very little foundation for this tale. Enormous numbers of fleas 

 are sometimes found in uninhabited apartments to which animals 

 have previously had access, and these fleas will attack in numbers 

 and with great eagerness any unfortunate person who may enter 



