XXII INTRODUCTION. 
2. Orthoptera, or straight-winged insects. This order comprises 
the crickets, grasshoppers, locusts, and similar insects. They 
have their upper wings of the consistence of parchment, and 
they have mandibles and maxillae. 
3. Hemiptera, or half-winged insects, have frequently half the 
upper wing membraneous, like the under ones, while the 
other half is leathery. To this division belong the bugs, the 
water-scorpions, the cicadce or froghoppers, and the aphides. 
These insects have neither mandibles nor maxillae, but in 
their place they have a sheath and sucker. 
4. Neuroptera, or nerved-winged insects, such as the dragon-flies, 
have both pairs of wings membraneous, naked, and finely 
reticulated. The mouth is adapted for mastication, and fur- 
nished with mandibles and maxillae. 
5. Hymenoptera, membraneous winged insects, such as bees, 
wasps, ichneumon flies, &c. All the four wings are mem- 
braneous, but they have fewer nervures, and are not reticu 
lated like those of the preceding order. The mouth is fur- 
nished with mandibles and maxillae, and the abdomen is ter- 
minated either by an ovipositor or a sting. 
(5. Lepidoptera, or scaly-winged insects. These are the butterflies 
and moths, and they are characterised by the farinaceous or 
scaly aspect of their wings, and the tubular or thread-like 
extension of the parts of the mouth. 
7. Strepsitera or Rhipiptera, with twisted wings. These crea- 
tures resemble the ichneumon, in laying their eggs in the 
bodies of other insects, though they generally attack wasps 
and bees. The principal genera are Xenos and Stylops. 
8. Diptera, or double-winged insects, including the flies. The 
mouth is furnished with a proboscis, and there are two small 
wings called halteres placed behind the true wings, which act 
as balancers. 
9. Suctoria, or sucking insects, such as the flea, which have no 
wings, but are furnished with an apparatus for sucking 
blood. 
SECTION II. Insects not undergoing Metamorphoses. 
10. Thysauoura, or spring-tail insects. These creatures are of small 
size, and without wings ; they are found in crevices of wood- 
work, or under stones. The principal genera are Leptisma 
and Podaurus. 
11. Parasita, or parasitical insects, such as the louse. They are 
also without wings. 
12. Myriapode. This order is made a separate class by many natu- 
ralists, as the creatures contained in it are distinguished from 
the true insects by the great number of their feet ; by the 
want of distinct divisions into thorax and abdomen ; and by 
the great number of segments into which the body is divided. 
The principal insects in this order are included in the Lin- 
