MOSQUITOES AND FLEAS. 



25 



Laboulbene describes carefully the pretty, oval, waxy white or 

 opaque, porcelain-colored, smooth egg, which reaches 0.5 mm. in 

 length. He describes the external appearance of the larvae and recites 

 their extremely rapid movements, which are made by means of the 

 bristles with which they are furnished, and particularly by means of 

 the tubercle and the hair-like spines below the head. He placed larvae 

 upon dust, with birds' feathers mixed with dried blood, upon which 

 they developed perfectly. Others were put on the sweepings of a room, 

 and developed just as well. Laboulbene at first believed that blood 

 was necessary for the nourishment of the larvae, the reddish-colored 

 contents of the digestive tract making him think so; but he found they 

 would nourish and complete their metamorphoses in sweepings in which 

 there was no trace of blood. He concluded that all that has been said 

 on Pulex irritans nourishing its young on dried blood is very problem- 



Fig. 5. — Pulex serraticeps ; a, egg; b, larva in cocoon; c, pupa: d, adult; e. mouth-parts of same from 

 side: /, labium of same from below: g, antenna of same— all enlarged (original). 



atical. In his opinion the larvae of the cat flea for the most part live 

 upon the ground in spots where cats stay, and that they live in the 

 dust in the cracks of the floor. The cocoon he described as ovoid, 

 almost rounded, brown and granular, because it is covered with dust. 

 delicate, but difficult to open, attached by one surface. It is about 

 2.5 mm. by 2.7o mm. The only statement in the article regarding the 

 length of the different stages is to the effect that the pupal condition 

 lasts from one to two weeks. 



Mr. Simmons found the eggs upon a cloth upon which a dog had 

 been sleeping, in the midst of a dust composed of fragments of cuticle, 

 hairs, fibers, and pellets of dried blood, the last being probably the nat- 

 ural excreta of the fleas. In fifty hours most of the eggs hatched. The 

 larvae are described, and the statement is made that in seven days they 

 began to spin their cocoons. They remained in the cocoons eight days. 



