152 



HOUSEHOLD INSECTS 



It has been found difficult to maintain just the right 

 degree of moisture for the larvae to thrive. The rearing 

 cages are either too moist or too dry and many of the 

 larvae die before reaching maturity. In his own work 

 with the larvae of the hen flea, Argopsylla gallinacea, the 

 author has had much difficulty in rearing them and was, 

 in fact, unable to rear any to maturity from the few eggs 

 he was fortunate enough to obtain. Mitzmain says that 

 the human flea develops very satisfactorily in material 

 composed of the sweepings taken from cracks in the floor. 

 It is quite probable that the great majority of larvae die 

 under the conditions in which they find themselves. 



It has long been a question regarding the food of the 

 larvae. Some authors have held that the adult human 

 flea fed its young upon dried blood. This is now thought 

 to be very improbable, for Laboulbene, a French investi- 

 gator, and Mitzmain of the United States have found that 

 the larvae would thrive and reach full growth simply on 



