262 OUR HOUSEHOLD INSECTS 



In the form of its larva, the flea is in complete agree- 

 ment with the order Diptera, the footless, jaw-bearing 

 maggot being, as we have seen, the usual type amongst 

 flies. 



The young flea does not enjoy a long larval life ; in 

 summer it becomes full-grown in about twelve days, and 

 then spins a little cocoon wherein to become a pupa. 

 This habit is apparently sometimes departed from, for 

 Rosel records that some of his larvae pupated without a 

 cocoon. The cocoon is, of course, extremely minute, and 

 to the silken threads of which it is composed are usually 

 attached particles of dust or cotton or woollen fibre, 



whereby its identity is al- 

 most completely obscured. 

 Inside the snug little abode, 

 the tiny maggot divests itself 

 of its larval skin, and ap- 

 pears as an odd, humpbacked 

 FIG. 8 3 . Pupa of Flea. (After chrysalis (Fig. 83). In this 

 the maggot shape has alto- 

 gether disappeared, and the outline of the perfect form 

 becomes evident. Legs for the first time appear, but 

 they are quite useless, as, in common with the rest of 

 the insect, they are encased in a thin investing pellicle, 

 each leg being enclosed in a case of its own. In the 

 character of its pupa the flea resembles the Hymen- 

 optera (ants, bees, wasps, &c.), and differs markedly 

 from the generality of the Diptera. 



The developing flea remains in the condition of a pupa 

 about a fortnight, of course taking no food during this 

 time; it is at first dirty white, but soon darkens and 

 assumes the well-known yellowish brown tint of the 

 adult. From this pupa issues the perfect flea, and then, 

 for the first time in its life, the spirit of bloodthirstiness 



