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As mentioned in the introduction, there are over 700,000 species of insects in our world, with some 10,000 new species being discovered every year. The variation in size, color, and shape is enough to boggle anyone’s mind.
How can anyone keep them all straight? And, how are true insects separated from other tiny creatures? Ticks, mites, spiders, and scorpions aren’t insects. Neither are centipedes, millipedes, or sowbugs.
Scientists use a system of classification. Every living and nonliving thing on earth fits into this system. No two names are the same. Once the name is given to a particular thing, there can be no doubt exactly what is being talked about.
The two major kingdoms of living things are plant and animal. The phylum gives a very general description of the animal. Humans belong to the phylum Chordata, along with every other animal with an internal backbone. Insects and spiders, and everything which has its skeleton on the outside are members of the phylum Arthropoda.
Classes narrow the possibilities further, followed by family, genus, species, subspecies, and so on. As the name grows longer, the description becomes more accurate, until it eventually defines one single kind of creature.
To see how it all fits together let’s look at the full names of a few pests you might encounter: Mosquito—Animalia Arthropoda Insecta Diptera Culicidae Culex pipiens
German Cockroach—Animalia Arthropoda Insecta Orthoptera Blattidae Blatella germanica
American Cockroach—Anima]ja Arthropoda Insecta Orthop tera Blattidae Periplaneta americana
Tick—Animalia Arthropoda Arachnida Acarina Ixodidae Rhipicephalus sanguineus
Black Widow— Animalia Arthropoda Arachnida Araneae The ridiidae Latrodectus mactans
You’ll notice that the first three belong to the class of Insecta, while the tick and black widow are Arachnida. This tells you that, other than being animals with an exoskeleton (Arthropoda), the first three have nothing in common with the last two.
It also tells you a few similarities that they do have.
All members of Insecta have six legs and three main body segments as adults. The three parts are the head, the thorax, and the abdomen. In most cases, the head has two antennae, a pair of compound eyes, and sometimes auxiliary simple eyes.
The three pairs of legs are located on the thorax, as are the wings, if they are present at all. The abdomen is the breathing and reproductive center.
Metamorphoses, or growth changes, occur in one of two ways. The incomplete (or gradual) metamorphosis is similar to that of humans. Out of the egg comes a nymph, which closely resembles the adult except in size. In most cases, this nymph lives in the same place as does the adult, and eats the same food. It gradually becomes an adult.
A complete metamorphosis begins with the egg. The egg hatches into a larva (like caterpillars and maggots). After a period of time the larva enters a pupa stage, often weaving a hard case (cocoon) around itself. During this period of apparent dormancy the larva loses its worm-like appearance and becomes a full-grown adult.
Flies have this second type of metamorphosis. When you see a small fly, don’t feel sorry for it because “it’s a baby.” What you see is the adult. It will never get any larger.
Arachnids differ in two respects from insects. Instead of having three body parts, they have only two. The head and thorax are a single fused piece. All the functions of an insect’s head and thorax are carried on here. The abdomen performs the same function in arachnids as it does in insects.
The second difference is in the number of legs. Insects as adults have six; arachnids have eight. In some species, the young arachnid may have only six, but will gain the other two after a few stages (instars) of growth. Each time it outgrows its “shell,” a molting takes place, like a snake shedding its skin.
Both insects and arachnids can be found worldwide, from the driest desert to the wettest jungle, from below sea level to the high mountains, and in an unbelievable range of temperatures. Their nests are found in the ground, in woods, trees, and plants, under or on water, inside animals, and a myriad of other places. One unusual variety of acari has been found thriving in a caustic solution of hydrochloric acid.
An insect’s food is almost as varied; everything from microscopic plant and animal life, to a full-grown elephant. (The infamous army ant, although totally blind, can kill an adult elephant and strip it to the bone in three days.)
In size, insects can be anything from the microscopic to huge creatures like the atlas moth of India, with a wing span of one foot, or the walkingstick from the same area which attains lengths of 15 inches. Certain species of the lowly cockroach get to be more than 6 inches long. (Relax. They aren’t in this country.)
Colors are usually “earthy,” but can be startling reds and blues. There are stripes, spots, patterns, and designs that would make Rembrandt jealous.
The truth about insects can be stranger than your wildest dreams. Even the common insects you come into contact with are amazing. Despite all of man’s effort to control or eliminate them, their numbers just haven’t dropped. While we’ve managed to make hundreds of species of larger animals extinct, our efforts seem only to encourage the insect. If we give them adverse conditions, instead of leaving, they adapt themselves to suit it, often within just a few generations.
Control can be an exasperating business because of that peculiar ability to adapt. But keep at it, and follow your common sense, and you’ll be able to at least control the majority of the pests around your home.
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