26 PRINCIPAL HOUSEHOLD INSECTS. 



when the adults emerged, completing their transformations seventeen 

 days after the eggs were deposited. 



The eggs of the flea under consideration are deposited between the 

 hairs of the infested animals, but are not fastened to them, so that when 

 the animal moves about or lies down numbers of the eggs will be dis- 

 lodged and drop to the ground or the floor or wherever the animal may 

 be at the time. An easy way to collect them, therefore, is to lay a stri^) 

 of cloth for the animal to sleep upon, and afterwards brush the cloth 

 into a receptacle, in which the eggs will be found in numbers. Some 

 difiiculty was found in securing proper conditions of moisture to bring- 

 about successful rearing, and some detailed account of our experience 

 will be of value to persons who desire to repeat the rearing in order to 

 secure material for microscopic study, and will be at the same time 

 suggestive as bearing on the conditions under which the insect will 

 multiply in houses. 



On June 27 a number of eggs were collected and placed in two glass 

 vessels, one large and one small, each containing a layer of sand at the 

 bottom, next a layer of sawdust, and on top of this a layer of rich soil. 

 The eggs were placed between two layers of blotting x^aper on top of 

 the soil. On June 29 fourteen of the eggs had hatched in the small 

 vessel, and the larva? had crawled at once down into the sawdust. 



On July 1 some of the eggs were found to have hatched in the large 

 vessel, and the alimentary canal of the larv;i> was already brownish, 

 indicating that they had been feeding to some extent and presumably 

 upon the particles of dried blood collected with the eggs and placed 

 with them between the layers of blotting paper. By July 11 all of these 

 larva? in both vessels had died, apparently without having cast a skin. 

 They were very active during most of this period, crawling rapidly 

 about when disturbed. Some were noticed to feed upon particles of 

 l^eat which was placed with them. From some of these individuals 

 fig. 6 was made. On the second antenna! joint there was apparent a 

 sensorial spot, and on or near the base of the antenu;^ were two small, 

 slender, fleshy tubercles and a few granulations on each side, some dis- 

 tance behind the antennjc. At the base of the head above occurred a 

 small, apparently well differentiated sclerite, as indicated in fig. 6, />, the 

 purpose of which we can not surmise. Immediately behind it, on tbe 

 anterior border of the first thoracic segment, is apparently a delicate 

 sculpturing, indicating a thickening of the integument at this x^oint. 

 The posterior border of this segment is a somewhat similar, faintly 

 indicated band. The first nine segments bear each four dorsal bristles 

 and, on each side, one ventrolateral bristle, near the posterior margin. 

 The two following segments bear each six dorsal bristles and one ventro- 

 lateral bristle, and the penultimate segment eight dorsal and one ven- 

 tral bristle. These bristles become gradually longer toward the end of 

 the body. The last segment is without long bristles, although there is 

 a semicircular transverse row of numerous fine hairs and a small patch 



