6 
INSECTS IN GENERAL. 
8quash-bug ( Coreus tristis J, the ocelli are wanting in the larva and pupa 
states, but become developed in the last or perfect stage. 
The compound eyes of insects present one of the most complex and 
beautiful mechanisms in the organic world. They are two in number, 
but proportionately very large, occupying in many insects nearly the 
whole of the sides of the head, and, in the dipterous order especially, 
often present across their disks, bands of the richest tints of green, 
brown and purple. These eyes are found to be composed of a great 
number of lesser eyes or eyelets, in the form of elongated cones so 
closely compacted as to form apparently a single organ. The larger 
ends of these cones point outwards, and by their union form the visible 
eye. Their smaller extremities point inwards, toward the brain, to 
which they afre connected by means of a large optic nerve. When one 
of these eyes is examined through a strong magnifying glass, it is seen 
to be composed of a very great number of little facets, sometimes 
square, but usually six sided, each one of which represents the outer 
and larger extremity of one of the component parts. These facets vary 
greatly in number in the eyes of different kinds of insects. In the ants 
there are about fifty in each eye ; in the Sphinx moths, about 1,300 ; in 
the house fly, 4,000 ; in the butterfly, upwards of 17,000 ; and in some of 
the small beetles of the genus Mordella, it is said that more than 25,000 
facets have been enumerated in one compound eye ; so that if we sup- 
pose that each of these component parts possesses the power of separate 
vision, one of these insects must have more than 50,000 eyes. How vi- 
sion is effected, or how a unity of impression can be produced by so 
complex an oi’gan, we are unable to couceive. 
Hearing . — Insects are evidently affected by loud noises, and moreover, 
as many insects have the power of producing voluntary sounds, it is 
reasonable to suppose that they possess the sense of hearing. No or- 
gan, however, which has been generally admitted to be an organ of 
hearing, has been discovered. It is the most common opinion of ento- 
mologists that the an ten me are instrumental in receiving the impres- 
sions of sound, and that the sense of hearing is located at or near their 
place of attachment to the head, and this view is much strengthened by 
the fact that in some of the larger crustaceans, such as the lobster and 
crab, a distinct organ of hearing is found located at the base of the an- 
tennae. 
Smelling . — That insects are endowed with the sense of smell, is proved 
by the fact that the carrion-fly, and other insects which feed upon, or 
deposit their eggs upon, putrescent matter, detect such substances at a 
distance, however completely they may be hidden from the sight. The 
bee also discovers honey under similar circumstances, and it is therefore 
fair to presume that insects are conducted to flowers, in hidden situa- 
