HOUSE FLEA. 47 



or birds. The antennae are small, usually sunken in a pit or groove 

 in the side of the head, and of peculiar form, the third or terminal 

 segment being annulated, or, in some cases, even divided into leaf-like 

 plates. The eyes are simple when present, but in many cases they are 

 reduced to mere rudiments, or even completely wanting. The tarsi 

 are five-jointed. 



"They undergo a complete metamorphosis,* the early stages being 

 passed in places adjacent to the resorts of the host. The eggs, while 

 sometimes laid upon the hairs of the host animal, are loosely attached, 

 and must ordinarily be scattered in places where the host-form sleep 

 or nest. The larvae, so far as known, live in dust or litter in similar 

 locations. They are slender, worm-like, footless objects, with a sparse 

 covering of hairs. The pupae form in similar locations, enclosing 

 themselves in cocoons. Westwood says : — ' When full-grown, which 

 occurs in summer in about twelve days, the larvae enclose themselves 

 in a small cocoon of silk, often covered with dust, and attached to 

 surrounding substances. Eosel, however, observed that some of the 

 larvae underwent their transformations without forming any cocoon.' " 

 — (H. 0., in work quoted.) 



The author further observes that, though Fleas are parasitic in the 

 adult stages, they are not strictly confined to the host animal, but 

 wander from it at times, and may even be found on different species 

 of animals from those which are evidently their regular hosts. 



The following further points of interest in the Flea life-history, 

 taken generally, are extracted from the very useful book mentioned 

 below f : — 



"The little Fleas are simply the males, which are considerably 

 smaller than the females. . . The males also differ in shape, and 

 have the hinder end of the body somewhat turned up." In Mr. 

 Butler's figures of a male and female Flea, plate v. of his work referred 

 to below, this difference in size and shape is very well shown. The 

 female Flea in the figure at p. 44, at heading of this paper, shows the 

 oval form of the extremity of the abdomen well, corresponding ni 

 shape with the photographed figure by Mr. Butler ; in the male, as 

 also shown in the figures by Mr. Butler and Dr. Taschenberg, the 

 lower part of the abdomen and appendages is turned up so that the 

 extremity forms a kind of terminal mass on a level with, or rather 

 higher than that of the line of the back of the abdomen, and divided 

 from it by a deep notch. The figure at p. 48 of the Cat and Dog 

 Flea gives some idea of this form in much magnified detail, and the 



* That is, they are not (like Grasshoppers and some other insects) almost 

 similar in general shape throughout all their stages. 



t ' Our Household Insects,' chap, xiv., by Edw. A. Butler, B.A., B.Sc. London : 

 Longmans, Green & Co. 



