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Because they are closely related, we include spiders, mites and ARTHROPOD pests.
You probably have about 1,000 species of insects living in your yard. They are all part of nature's complex ECOSYSTEMS and FOOD CHAINS. Of the nearly 100,000 insect species in the USA, only about 600 species are considered pests. Since few insects are actual pests, Master Gardeners must learn which are pests, which are BENEFICIALS, and which do not affect gardening.
Pest insects and mites may feed on our plants and our homes, or they may carry diseases that infect plants. A few also carry diseases that infect animals, including people. Master Gardeners use the term "pest management" rather than "pest control" or "pest eradication." We cannot eradicate or completely rid our gardens and homes of pests. We can only try to control them.
ARTHROPODS
Insects are a class or subgroup of a larger group called of phylum, known as arthropods (ARE-throw-pods). This word means "jointed foot." The arthropod group includes insects, spiders, crayfish, millipedes and similar animals. The various groups within the arthropods are distinguished from each other by the arrangement of their body parts.
INSECTS
Insects are land animals with 3 pairs of jointed legs. The insect group includes many subgroups: termites; grasshoppers, crickets and roaches; earwigs; lice; true bugs; beetles and grubs; butterflies, moths and caterpillars; fleas; flies, gnats and maggots; and bees and wasps.
People often refer to insects as bugs. This is incorrect. Bugs are a subgroup of insects, just like the beetles, flies, bees and wasps.
BODY PARTS
There are three characteristics found among all insects:
3 body regions: head, thorax (THOR-ax) and abdomen (AB-doe-men)
1 pair of antennae (an-TEN-e)
3 pairs of legs attached to the thorax
None of the arthropods, including insects, have a skeleton of bones. Instead, they have a tough outer shell called an exoskeleton. The exoskeleton provides support and protection. In order to grow, arthropods must shed the exoskeleton or molt.
ARACHNIDS
This class is relatively small, but important. They have the following body characteristics:
two body regions: cephalothorax (head/thorax) and abdomen
four pairs of legs attached to the cephalothorax
pincher-like mouthparts
Although spiders frighten people, they are generally helpful to humans. They are shy and only can distinguish objects within a few inches from them. Even poisonous spiders are not aggressive.
BODY PARTS
The arachnids have the following body parts:
2 body segments: head/thorax and abdomen
4 pairs of legs
All arachnids have exoskeletons like insects, but they have no antennae or wings. The following illustration shows a typical spider, next to a typical insect.
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