INDIAN BLOOD-SUCKING INSECTS. 
661 
immature stages are purely terrestrial, but in practically all species 
belonging to the remaining families of blood-suckers we find semi-aqua- 
tic or purely aquatic larvae : these families may be arranged roughly in 
the order Tabanidce and Psychodidce (genus Phlebotomies), Chironomidce 
(genus “ Ceratopogon ”), Simuliidce and Culicidce. 
The larvae and pupae of the last two families are purely aquatic ; the 
larvae of Tabanidce and Phlebotomies live in mud, slime, or wet earth, and 
seek a comparatively dry spot in which to pupate, while the larvae of 
Ceratopogon are of two kinds, some living under bark and in similar damp 
shady places, while others are purely aquatic and agree in this respect 
with the numerous species of non-blood-sucking Chironomidce. We may 
make a further generalization by saying that in these families with 
aquatic or semi-aquatic larvae it is only the female that sucks blood, 
whereas in the purely terrestrial families both sexes may do so. None 
of the former group spend any very appreciable portion of their lives on 
the victim, whereas several of the latter do. 
As to the numerical ratio between blood-sucking and non-blood¬ 
sucking species, this varies in the different families to a considerable 
extent. Excepting a very few particular cases, we may say that at least 
one sex of all species of Siphonaptera, Pupipara, Tabanidce, Simuliidce, 
and Culicidce suck blood, but of the total number of species of Muscidce, 
Psychodidce and Chironomidce only a very small percentage have the 
habit : this paucity of species unfortunately does not mean that the 
number of individuals of these three families is any the less, for most of 
us have had abundant opportunities of observing the prevalence of 
sand-flies ( Phlebotomus ) at certain seasons of the year, although the 
number of species of this blood-sucking genus probably does not repre¬ 
sent five per cent, of the total number of harmless species in the family 
to which it belongs. The same is true in an even greater degree of the 
Midges ( Ceratopogon, family Chironomidce) and: of the blood-sucking 
Muscidce, for they constitute only a very small fraction of the total 
number of species in their respective families. 
As regards the second Order, Rhynchota, which includes blood¬ 
sucking species among its members, we find again that these form only 
quite a small proportion of the Order as a whole. Among the Lice 
(.Pediculidce )* are species which pass their whole lives from egg to adult on 
the body of the host, and whose structure has evidently undergone 
great modification to fit them for a purely parasitic existence. The 
Bugs (Cimicidce), though often remaining for some considerable time on 
the body of the host (generally man), usually pass the greater part of 
their lives elsewhere, and seek their victim only when wanting blood. 
The results of recent work on the relations which exist between the 
life of blood-sucking insects on the one hand, and on the other the life of 
man and of those animals which he breeds for his pleasure and profit, 
have shown an unexpectedly close connection between the two, and of this 
* Often classed as.a distinct order Anoplura. 
