268 
Sense of Smell in Insects . 
May, 
larva, whether it resembles the mature insect in shape or 
not, are minute and simple. Indeed careless observers take 
an incredulous look if they hear mention of the antennae of 
a caterpillar. 
The distinction between diurnal and nodturnal species is 
often very plainly marked. If we take the most typically 
diurnal beetles, the tiger-beetles, the Harpalidae, the Bupres- 
tidae, the majority of the Elateridae, we find the antennae 
made up of linear portions like threads or bristles. Of the 
forms which have clavate, flabellate, or peCtinate antennae, 
a large part are nocturnal. Among Lepidoptera the case is 
very similar. The plumed antennae, so common among the 
night-flying moths, are quite unknown among their diurnal 
kindred, the butterflies. 
Of all inserts those possessing the greatest locomotive 
power are probably the dragonflies. Here, accordingly, we 
find the antennae very short and simple, never having more 
than eight joints, and being attenuated instead of enlarged 
at the tip. On the other hand, great complication of struc- 
ture is met with in groups which are slow on foot, which 
take wing with difficulty, and do not steer well when flying, 
—all which attributes are well marked in the great family of 
Lamellicornes. 
Of omnivorous inserts we may take the common house-fly 
as a type. Scarcely any kind of organic matter comes amiss 
to its latitudinarian tastes, and here accordingly we find 
antennae of three joints only. With such forms we may 
usefully contrast the carrion-beetles which do not ordinarily 
make use of any other kind of food, and whose antennae all 
terminate in a jointed club, formed as if of a number of flat 
plates laid one over another, and, though joined together at 
their centres, yet detached round the circumference so as to 
expose a large surface to the air and the action of fumes and 
odours. Again, we may take the enormous family of Curcu- 
lionidae. Almost every species of this multitude is restricted 
for its food to a single plant or to a group of closely-allied 
forms, and here accordingly we see the antennae always ter- 
minating in a club. 
Of the simplicity of these organs in Epizoa the fleas and 
lice are a good instance. On the other hand, the Ichneu- 
monidae — which, though parasitic in their earlier stages, 
have, when mature, to lead an aCtive life, and to search out 
an appropriate habitation for their young — have very long 
and highly-developed antennae. 
As an instance where the evolution of the eyes is comple- 
mentary to that of the antennae, we may take the same 
