Explanation of Terms Used in Entomology Informative Summary

This glossary was written in 1906 by John Bernhard Smith, a professor of entomology at Rutgers College. It aimed to provide a comprehensive collection of terms used in the field of entomology, encompassing anatomy, physiology, and ecology. Smith acknowledged the rapid growth of the discipline, resulting in diverse terminology and even multiple meanings for the same terms. He included a substantial number of terms from various subfields, with particular focus on insect morphology.

Key findings:

  • The glossary reflects the state of entomological knowledge in the early 20th century, providing insights into the development of the field.
  • The inclusion of numerous terms specific to different insect orders and families highlights the diverse and specialized nature of entomology.
  • The extensive use of Latin and Greek terms in the glossary indicates the influence of classical scientific languages on the field.

The reader will learn:

  • A vast array of terms related to insect anatomy and morphology, helping them understand and describe the structures of insects.
  • The definitions for these terms will help readers understand how entomologists classify and categorize different insect parts and features.
  • The glossary’s organization, grouping terms alphabetically with definitions, examples, and historical context, will equip the reader with the tools for comprehending and communicating about entomology.

Historical context:
The glossary was published in 1906, a time of significant scientific advancements. The text reflects the ongoing exploration and development of the field of entomology. Smith highlights the challenges of maintaining consistency in terminology due to the rapid growth of the discipline. He acknowledges the need for collaboration and ongoing refinement of entomological terminology.


  • The term “Entomology” comes from the Greek words “entos” meaning “within” and “logos” meaning “study.”
  • Cantharidin, the blistering substance produced by meloid beetles, has the chemical composition C10H12O4.
  • The North American transition zone, where boreal and austral faunal elements overlap, is divided into humid, arid, and Pacific coast humid areas.
  • The complete metamorphosis of insects consists of four distinct stages: egg, larva, pupa, and adult.
  • The wings of insects are supported by a chitinous framework of veins, forming a network that is crucial for flight.
  • The compound eyes of insects are made up of numerous facets, each with a lens that forms a partial image.
  • The salivary glands of insects secrete digestive enzymes, irritants, or viscid substances.
  • The malpighian tubules, resembling kidneys, serve as excretory organs in insects.
  • The brain of insects is composed of three primary ganglia: the protocerebrum, deutocerebrum, and tritocerebrum.
  • The trachea, air-filled tubes branching throughout the body, are the respiratory organs of insects.
  • Insect larvae can undergo a process called molting, shedding their exoskeleton as they grow.
  • The term “ento-parasite” refers to a parasite that lives within the body of its host.
  • The term “myrmecophily” refers to the symbiotic relationship between ants and other insects.
  • The “sub-clypeal pump” is a muscular structure in the pharynx of some Diptera, used to draw in food.


  • There are over 1 million known species of insects, representing the largest class of animals on Earth.
  • The United States transition zone is divided into three distinct faunal areas: Alleghanian (humid), arid transition, and Pacific coast humid.
  • The order Hymenoptera encompasses approximately 150,000 species, including bees, wasps, and ants.
  • The order Coleoptera, or beetles, includes over 350,000 known species.
  • The order Diptera, or flies, includes around 160,000 known species.


  • Antennal segment: The second or deutocerebral segment of the head.
  • Arculus: A small cross-vein between radius and cubitus near the base of the wing.
  • Clypeus: The portion of the head before or below the front, to which the labrum is attached.
  • Elytra: The hardened, leathery forewings of beetles, which serve as protective covers for the hind wings.
  • Frenulum: A small spine or ligament that connects the forewings and hindwings in some Lepidoptera during flight.
  • Halteres: The small, club-shaped structures in Diptera, representing modified hindwings, which function as balancers during flight.
  • Ocellus: A simple eye, found in larvae and sometimes adults, which provides a limited field of vision.
  • Prolegs: The fleshy, unjointed abdominal legs of caterpillars and some sawflies.
  • Scutellum: The third dorsal sclerite of the meso- and meta-thorax, a triangular piece between the elytra at base.
  • Tegulae: Small, scale-like structures at the base of the forewings in Hymenoptera, Lepidoptera, and Diptera.


  • Batesian Mimicry: The viceroy butterfly (Limenitis archippus) mimics the monarch butterfly (Danaus plexippus) in appearance. The monarch is distasteful to predators, so the viceroy, which is palatable, benefits from the mimicry.
  • Müllerian Mimicry: Both the monarch butterfly and the queen butterfly (Danaus gilippus) are distasteful to predators. They share similar warning coloration, reinforcing the predator’s aversion to both species.
  • Caterpillar Tubercles: The abdominal segments of caterpillars often bear a variety of tubercles, including: anterior trapezoidal, posterior trapezoidal, lateral, posterior stigmatal, anterior stigmatal, sub-primary subventral, pedal, and adventral tubercles. Each type of tubercle has a specific location and number of setae, which can be used for identification.
  • Saltatorial Legs: Grasshoppers, locusts, and crickets have hind legs that are adapted for jumping. These legs are significantly larger and more muscular than the forelegs and middle legs.
  • Scent Glands: Male moths often have scent glands, called androconia, which release pheromones to attract females. These glands can be located on the wings, antennae, or abdomen.
  • Stridulation: Crickets produce a chirping sound by rubbing their forewings together. The scraper on the inner margin of one wing rubs against a file on the outer margin of the other wing.
  • Honey Tubes: Aphids, plant lice, produce honeydew, a sugary secretion, from their honey tubes, which are small, tube-like structures on the abdomen. This secretion is attractive to ants, which sometimes protect aphids from predators.
  • Galls: Gall wasps (family Cynipidae) produce galls by injecting eggs into plant tissue, causing the plant to grow abnormally. The larvae feed on the gall tissue until they emerge as adults.
  • Complete Metamorphosis: Butterflies undergo a complete metamorphosis, passing through the egg, larva, pupa, and adult stages. During the larval stage, the caterpillar feeds and grows, transforming into a pupa. The pupa is an inactive, non-feeding stage, where metamorphosis occurs, resulting in the emergence of an adult butterfly.

Conclusion: This glossary of entomological terms is an invaluable resource for anyone interested in learning about insects. It covers a vast range of terminology, providing definitions, examples, and historical context. By understanding the language of entomology, readers can better appreciate the complexity and diversity of the insect world. Smith’s glossary is a testament to the ongoing evolution of entomological knowledge and its reliance on a rich and dynamic vocabulary.

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