Insects
Author: Ray Bowers

Description:
The insects are the largest group of animals, with over 750,000 described species, in fact there more type of insects then all other types of animals combined. They first appeared during the Devonian Period about 400 million years ago. Insects have three distinct body regions: the head, thorax, and abdomen. The head contains the mouthparts, a pair of antennae, and a pair of compound and/or simple eyes. The thorax region has three pairs of legs and most insects also have wings.

Insects have a respiratory system that is made of a series of tube called trachea that spread throughout the body. The digestive and nervous system is similar to the ones described for the rest of the Phylum Arthropoda.

Geographic range:
Insects are found world wide.

Habitat:
Insects are found in all terrestrial habitats and in shallow aquatic habitats.

Food Web:
Insects occupy all consumer parts of the food web, and some have specialized to become external parasites.

Reproduction and Development:
All insect groups have sexual reproduction, however some types of insects can reproduce without fertilizations, which is called parthenogenesis. Most insects lay eggs in a suitable environment, but some give birth to living young.

There are two basic types of development after hatching from the egg. Simple or incomplete metamorphosis starts with the egg, a number of immature stages or nymphs, and then the adult stage.

During complete metamorphosis the egg leads to a larval stage, then a pupa or resting stage, and finally the adult stage.

Behavior:
Insects display a wide range of behaviors. Most insects are solitary, but some form organized societies.

Insects defend themselves by using unpleasant chemicals, stings. or biting. They may escape by running, hopping, or flying away. Some insects use camouflage to protect themselves, not just to hide, but sometimes to mimic another insect, such as flies mimicking bees.

Insects use a variety of communication behaviors. Some insects use bright colors to communicate, others use light or sound. Chemical communication is common; these chemicals are called pheromones. Pheromones can be used to attract a mate, raise an alarm, leave a trail, or determine an insect's place in society.

Some insects migrate a short distance from one area of their habitat to another, while others may migrategreat distances like the monarch butterfly. Basically any behavior that can be thought of insects of one kind or another will be doing it.

Ecosystem roles:
Insects play an important role in all aspects of the environment, from predator to prey to decomposer. Because of the dry conditions, insects are very important as decomposers in the Chihauhaun Desert.

Some insects form symbiotic relationships such as mutual or parasitic relationships. In a mutual relationship both members benefit, such as the yucca moth pollinating the yucca plant and the yucca plant providing food for the moth larva. In a parasitic relationship one member is benefited and the other is harmed, such as the bot fly larva living on a pack rat.

Insects also play a role in the physical environment insect burrows allow air and water to circulate through the soil. This is especially important in the desert.

• Insect populations vary form being very abundant, in some cases to the point of being pest to being rare or endangered of becoming extinct.
  
• Some insects carry diseases, such as West Nile Virus or parasites such as Malaria.

Taxonomy:

Kingdom: Animalia
Phylum: Arthropoda
Class: Hexapoda, insects

The following 28 orders occur in New Mexico:

Protura
Collembola: springtails
Diplura
Microcoryphia: bristletails
Thysanura: silverfish
Ephemeroptera: mayflies
Odonata: dragonflies and damselflies
Phasmida: walkingsticks
Orthoptera: grasshoppers, crickets, and katydids
Mantodea: mantids
Blattaria: roaches
Isoptera: termites
Dermaptera: earwigs
Embiidina: webspinners
Plecoptera: stoneflies
Psocoptera: book lice
Phthiraptera: lice
Hemiptera: true bugs
Homoptera: cicadas, hoppers, aphids, and scale insects
Thysanoptera: thrips
Neuroptera: lacewings and antlions
Coleoptera: beetles, such as tiger beetles or darkling beetles
Strepsiptera; twisted-wing parasites
Siphonaptera: fleas
Diptera; flies
Tricoptera: caddisflies
Lepidoptera: butterflies and moths
Hymenoptera: wasps, bees, and ants, such as tarantula hawk wasp or rough harvester ant

References:
Borror, Donald J. and Richard E. White. 1970. A Field Guide to the Insects of America North of Mexico. Boston: Houghton Mifflin Co.

Barnes, Robert D. 1980. Invertebrate Zoology. Philadelphia: W. B. Saunders Co.

Borror, Donald J., Charles A. Triplehorn, and Norman F. Johnson. 1989. An Introduction to the Study of Insects. Philadelphia: W. B. Saunders Co.

Bland, Roger G and H. E. Jaques. 1978. How to Know Insects. Dubuque, Iowa: Wm. C. Brown Co.

Larson, Peggy and Lane Larson. 1977. The Deserts of the Southwest. San Francisco: Sierra Club Books.

MacMahon. James A.1985. Deserts. New York : Alfred A Knopf, Inc.

Werner, Floyd and Carl Olson. 1994. Insects of the Southwest. Fisher Books, LLC.

Related Terms: Atelocerata, Hexapoda, Arthropoda