On the criteria of species diversity, distribution,
and sheer numbers, insects must be regarded as the most successful
class of animals ever to live. There are over 700,000 species of insects
known, outnumbering all other forms of life combined. They are distinguished
from other classes in the Phylum Arthropoda by having a body divided
into three main parts: head, thorax, and abdomen.
Jointed Feet
All arthropods, including insects, are equipped with jointed appendages,
for which the phylum is named (from the Greek arthron, "joint,"
and podus, "foot").
The appendages are variously modified for walking, feeding, sensory
perception, copulation, and defense. Several pairs of appendages
modified for piercing, sucking and chewing form the mouthparts;
the insect mouth is a very busy place when all its dexterous parts
go to work on a piece of food.
Reproduction
In insects, reproduction is usually sexual, with separate male
and female individuals. Fertilization is usually internal. In most
species, sperm are deposited directly into the female's vagina at
the time of copulation, though in some species the male deposits
a sperm packet outside the female, who then picks it up. The female
reproductive system may also include a spermatheca, a blind sac
in which sperm may be stored for a year or more.
Though most insect species produce a multitude of eggs, some flies
produce live offspring, usually a single young at a time. Many insects
mate only once in a lifetime.
External Skeleton
The body of an insect is completely covered by the cuticle, an
exoskeleton (external skeleton) constructed from layers of protein
and chitin. The cuticle can be modified into a thick, hard armor
over some parts of the body or be paper-thin and flexible in other
locations, such as the joints of the appendages.
The exoskeleton protects the animal and provides points of attachment
for the muscles that move the appendages. To grow, an arthropod
must occasionally shed its old exoskeleton and secrete a larger
one, a process called molting.
Many insects have one or two pairs of wings that attach to the
dorsal side of the thorax. Since the wings are believed to have
developed from basal parts of the legs rather than whole appendages,
insects are able to fly without sacrificing any walking legs.
Endangered Species
There are many, many different kinds of terrestrial and freshwater
invertebrates in British Columbia. Most of these invertebrates are
arthropods - insects, spiders, and their relatives. It is not known
how many invertebrates can be found in the dry, warm lowlands of
the south Okanagan and Similkameen valleys, but we estimate that
perhaps 15 000 species live there.
Although many of these are common and widespread, some are confined
to the dry grasslands of the southern Interior - and there are literally
hundreds that are found nowhere else in the province. These are
inhabitants of the Great Basin grasslands and wetlands, which extend
only a few, narrow fingers north into Canada. Several species of
insects that are considered rare in this region include:
Beetles
The endangered Dark Saltflat
Tiger Beetle (Cicindela parowana), is an example
of the Order Coleoptera (Beetles). Main characteristics of these
animals are that they have two pairs of wings, the front ones are
horny covers protecting the membranous hind wings. They have biting
and chewing mouthparts and complete metamorphosis.
Dragonflies
The endangered Vivid Dancer
(Argia vivida), is an example of the Order Odonata,
the Dragonflies. This order has two pairs of net-veined wings; biting
mouthparts and an incomplete metamorphosis.
Mantids
The endangered Ground Mantid
(Litaneutria minor), is an example of Order
Mantodea. The main characteristics of most species within this order
include: elongate thorax and grasping front legs; two pairs of wings,
the front ones leathery, the hind ones membranous (wings are sometimes
reduced); biting and chewing mouthparts; and an incomplete metamorphosis.
Flies
The endangered Apiocerid Fly
(Apiocera barri) and the threatened Robber
Fly (Megaphorus willistoni), are examples of the
Order Diptera. Mosquitoes are also members of this order and possess
the same main characteristics as these flies: one pair of wings
and, the hindwings modified to form balancing halteres; sucking,
piercing, lapping mouthparts; and complete metamorphosis.
Butterflies and Moths
The endangered Mormon Metalmark
(Apodemia mormo) and the extirpated Viceroy
(Limenitis archippus), are examples of Order Lepidoptera,
the Butterflies and Moths. Species belonging to this order share
the characteristics of having two pairs of wings covered with scales;
hairy bodies; tubular mouthparts forming a long coiled tongue for
sucking; and complete metamorphosis.
Ants, Bees and Wasps
The endangered Scoliid Wasp
(Campsomeris pilipes) is an example of the Order
Hymenoptera. Ants, bees and wasps belong to this order because they
display the same main characteristics: two pairs of membranous wings;
head mobile; well-developed eyes; chewing or sucking mouthparts;
stingers (in some species); complete metamorphosis; and many species
are social.
The Thompson-Okanagan and Similkameen valleys of southern British
Columbia contain all of these species and more that are endangered
for a variety of reasons. Insects in these regions are primarily
threatened by loss or degradation of their habitats and are at risk
because their ecosystems are at risk.
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