CHAPTER 1 INTRODUCTION: PESTS AND THEIR RELATIVES 

    Plants in their many forms from great trees to tiny mosses cover the land. The plant kingdom began as microscopic single cells - pond scum. Their descendants are the algae, bacteria and fungi living today. Larger prehistoric plants developed from their smaller ancestors; finally, flowering plants, modern shrubs, and trees evolved.
     Forebears of insects were the first animals to move onto land - before plants had flowers. As plants developed, so did the insects, feeding on evolving plant structures, such as flowers, pollen, nectar, leaves, bark, stems, roots, and their dead remains. At the time of early insect development, the land had a uniform climate: one with moisture and temperature adequate for constant growth. Later, the surface land mass (continents) shifted, moving northward and southward, creating seasons, and setting the stage for the world as we know it. 

THE INSECT PLAN 
Insects and their Relatives 
Living things are divided into the Plant Kingdom, the Animal Kingdom, and several smaller kingdoms that include microscopic life. Insects are in the largest group in the animal kingdom - the Phylum Arthropoda. In this group the "arthropods" include spiders, mites, ticks, millipedes, centipedes, crabs, shrimp, and insects.

 Phylum Arthropoda Arthropod classes have: |

Principal classes into which the phylum Arthropoda is divided include: 

Arachnida 
This class includes spiders, mites, scorpions, daddy long legs and others. These arthropods usually have mouthparts with two prominent structures that end in a needle-like piercing tip. They have four pairs of legs and two body regions: the mouthparts and legs are attached to the first region; the reproductive organs and digestive system is contained in the second.

Crustacea 
This class mostly includes aquatic crabs, lobsters, and shrimp as well as crustacea that dwell on land, pill bugs and sow bugs.

Myriapoda
This group is made of two classes -- millipedes and centipedes. The millipedes are many-segmented and worm-like; they are cylindrical with short antennae and two pairs of legs per segment.
Centipedes are also many-segmented and worm-like, but they appear more flattened; with one pair of legs per segment; antennae and hind legs are long (All legs of the house centipede are very long).

Insecta
This class contains the insects: arthropods with three body regions - head, thorax and abdomen. The head bears a single pair of antennae; the thorax bears three pairs of legs, usually wings; the abdomen contains most of the digestive system and the reproductive organs.

Other Divisions Used in Classification
    Classes of arthropods, insects, for example, are divided into orders. These are distinct groups that look very much alike (e.g., the order of moths and butterflies, or the order of beetles).
     Orders are subdivided into families made up of related species. Species of animals can be thought of as "kinds of animals". Very closely related species are grouped together in a genus. Species or types of a body made of segments, which are grouped or fused together legs, antennae and other appendages attached in pairs a hard or tough external covering with some pliable, or soft parts; an arthropod outer body that holds the body together and gives it shape. [It performs the same function as the mammal's bony internal skeleton, and is called an exoskeleton]. animals (and plants) are given scientific names that always consist of two words; the first word is the genus name (the first letter is always a capital), the second is the species name (always lower case). Both are written in italics or underlined (e.g., Musca domestica). Well-known species can be given nonscientific names, called "common names" (e.g., house fly).

GROWTH AND DEVELOPMENT

Growth

The arthropod body is confined in its exoskeleton. This outer covering can expand only a little at pliable or soft places. It does not grow continuously. Arthropods grow in stages. They form a new soft exoskeleton under the old one, then shed or molt the old one. The soft new one fits the accumulated growth. The new exoskeleton is white at first, but it hardens and darkens in a few hours. After the molting process, which usually takes place in hiding, the arthropod resumes its normal activities.

Development

Arthropods hatch as tiny individuals and grow by molting, usually keeping the same appearance until they become adult. [The reader will find that a spectacular and very important exception occurs in the class Insecta.)

The insect class is divided into groups according to the way insects change during their development. This change is called by the technical term, metamorphosis, which means "change in form". Three main types of metamorphosis have been identified.

 Group 1. Simple Metamorphosis

This group including the order of springtails and silverfish, makes no drastic change. They simply hatch and grow larger by molting periodically. Three small orders are included together in this group.

 Group 2. Gradual Metamorphosis

In this group (e.g., cockroaches, crickets, grasshoppers, boxelder bugs, earwigs, etc.),nymphs, do not have wings. (Winged insects are always adults and have finished their growth.) Fourteen orders develop in this way. Some of these orders have many species and include many pests. Nymphs and adults are often found together and eat the same food.

Group 3. Complete Metamorphosis

The orders that develop by complete metamorphosis make a complete change in appearance. These orders contain the majority of insect species. In fact, they number more than all of the other species in the entire animal kingdom! This major group consisting of nine orders, includes beetles, moths and butterflies, flies, fleas, and the stinging insects, ants, bees and wasps.

Insects with complete metamorphosis hatch from eggs as larvae, (grubs, maggots and caterpillars). The mission of the larval stage is to feed and grow. Larvae continue their development through a number of molts until they become mature; then, they change into pupae. Not active like larvae; the purpose of the pupal stage is one of change or body rearrangement resulting in a complete change into the adult stage. The mission of the adult is to reproduce.

 Considerations of Pest Management

These developmental stages of insects with complete metamorphosis support rather than compete with each other. It is as if the single species is represented by two or three completely different animals with different needs and habits: The larvae feed and live in one spot; they sometimes leave that spot to pupate a short distance away. The adult emerges and often lives in another area, returning to the larval feeding site only to lay eggs. For this reason, pest controllers manage species with complete metamorphosis in different ways according to the different stages, where each lives, and what they do. The reader will want to pay special attention to sections that discuss the growth cycle, behavior, and harborage (the area in which the animal lives and finds its food) of each animal.