FLEAS AS PESTS TO MAN AND ANIMALS. 3 
The insect remains within the cocoon for a period which may 
range from three days to more than a year. The cocoon of the dog 
flea is illustrated in figure 1 at >. The dark curved object within is 
the larva just before pupating. 
The complete life cycle of members of this group of eee may 
be passed in as short a period as 19 days, but during cool weather 
Fic. 1.—The dog flea: a, Egg; 6b, larva in cocoon: c, pupa; d, adult; e, mouth parts of 
same from side; f, antenna; g, labium from below. 6b, c, d, Much enlarged: a, e, f, 9, 
more enlarged. (From Howard.) 
or under adverse conditions the total period from egg to adult may 
extend considerably over a year. 
HOW LONG THE ADULT WILL LIVE. 
The length of life of the mature flea varies much in different 
species and also under different atmospheric conditions. During 
lic. 2.—The European rat fea: Larva. Greatly enlarged. 
(Author’s illustration. ) 
hot, dry weather, and when no animals upon which to feed are 
present, the duration of life is exeremtly short—two ‘to five days 
When allowed to feed on blood, which is the only food taken by the 
adults, they may live from a month to almost a year. During sum- 
