Insect Orders

Overview of Insect Orders

Classification
Animals are classified into the animal kingdom. Each kingdom is then further divided into increasingly smaller groups based on similarities. The different levels of groups are named by the convention of taxonomists (scientists who study classifications). The standard groups in a typical complete classification of species are (the example is for a honey bee, Apis mellifera Linnaeus)

There are often additional groups used that are intermediate to the groups listed. These groups often use a prefix of super- (above) or sub- (below) to indicate the position of the new group in the above list. Thus, superfamily groups fall between order and family while subfamily groups fall between family and genus. An insect name is complete if the genus, species and author names are given because of the rules that govern taxonomy. The author is the person who first described the species as new to science.

Terminology, Classification and Use of Scientific Names

No capital letters are used in common names unless they contain a proper noun. Common names are written as two words if the species actually belongs to that classification, e.g., honey bee, or as one word if not within the classification, e.g., sawfly is not in Diptera, the order containing true flies.

Scientific names (genus, species and subspecies) are italicized or underlined with the genus (first) name capitalized. Names of the authors of species follow. These names are in parentheses if the classification of the species has changed since it was described.

In this book approved common names, scientific names and authors used generally follow Stoetzel (1989). Common names are generally in bold letters, although bold insect names in parentheses are not approved common names. Scientific names and order of presentation of taxonomic groups generally follow Borror et al. (1989).

Insects belong to a larger group call Arthropoda which includes all animals with segmented legs, segmented bodies and exoskeletons. The phylum Arthropoda includes: spiders, ticks, mites, centipedes, millipedes, shrimps, lobsters, and many other organisms. Entomology is concerned primarily with the study of two classes belonging to:

• 1. Class Hexapoda or Insecta – (insects)
  2. Class Arachnida – (spiders, ticks, mites, scorpions, and relatives).

However, some other arthropod classes like Diplopoda (millipedes) and Chilopoda (centipedes) are often considered by entomologists. Even a few non-arthropod groups like snails and slugs (Phylum – Mollusca) are sometimes referred to entomologists.

Class Hexapoda (Insecta) Insect Characteristics

Most adult insects have the following characteristics:

• 1. A body divided into three parts (head, thorax and abdomen)
  2. Three pairs of legs
  3. Usually one pair of antennae and a pair of compound eyes (a few exceptions to these characteristics are found)
  4. Usually two pairs of wings (absent in many insects such as lice, fleas, ants; flies have one pair of wings)

Insect Orders – Introduction

The Class Hexapoda is generally studied under a classification system with approximately 30 orders. Many of these are of minor importance and are studied only from the standpoint of scientific interest. Considered here are some of the more important orders which are likely to be encountered. Many taxonomists disagree on the number of orders and their names. Thus, this scheme will often vary with different authors.