A dragonfly is a flying insect belonging to the infraorder Anisoptera below the order Odonata. About 3,000 extant species of true dragonflies are known. Most are tropical, with fewer species in temperate regions. Loss of wetland habitat threatens dragonfly populations around the world. Adult dragonflies are characterized by a pair of large, multifaceted, compound eyes, two pairs of strong, transparent wings, sometimes with coloured patches, and an elongated body. Many dragonflies have brilliant iridescent or metallic colours produced by structural colouration, making them conspicuous in flight. An adult dragonfly's compound eyes have nearly 24,000 ommatidia each.
Damselflies are flying insects of the suborder Zygoptera in the order Odonata. They are similar to dragonflies, which constitute the other odonatan suborder, Anisoptera, but are smaller and have slimmer bodies. Most species fold the wings along the body when at rest, unlike dragonflies which hold the wings flat and away from the body. An ancient group, damselflies have existed since at least the Lower Permian beginning about 299 million years ago, and are found on every continent except Antarctica.
Mayflies are aquatic insects belonging to the order Ephemeroptera. This order is part of an ancient group of insects termed the Palaeoptera, which also contains dragonflies and damselflies. Over 3,000 species of mayfly are known worldwide, grouped into over 400 genera in 42 families.
Sarcoptes scabiei or the itch mite is a parasitic mite that burrows into skin and causes scabies. The mite is found in all parts of the world. Humans are not the only mammals that can become infected. Other mammals, such as wild and domesticated dogs and cats as well as ungulates, wild boars, bovids, wombats, koalas, and great apes are affected.
The most recent understanding of the evolution of insects is based on studies of the following branches of science: molecular biology, insect morphology, paleontology, insect taxonomy, evolution, embryology, bioinformatics and scientific computing. It is estimated that the class of insects originated on Earth about 480 million years ago, in the Ordovician, at about the same time terrestrial plants appeared. Insects are thought to have evolved from a group of crustaceans. The first insects were landbound, but about 400 million years ago in the Devonian period one lineage of insects evolved flight, the first animals to do so. The oldest insect fossil has been proposed to be Rhyniognatha hirsti, estimated to be 400 million years old, but the insect identity of the fossil has been contested. Global climate conditions changed several times during the history of Earth, and along with it the diversity of insects. The Pterygotes underwent a major radiation in the Carboniferous while the Endopterygota underwent another major radiation in the Permian.
Erythemis simplicicollis, the eastern pondhawk, also known as the common pondhawk, is a dragonfly of the family Libellulidae, native to the eastern two-thirds of the United States and southern Ontario and Quebec, Canada. It is a dragonfly of ponds and still waters. The species is distinguished in that the female is bright green with a banded abdomen and the mature male has a blue abdomen with a green face and green and blue thorax.
The common walkingstick or northern walkingstick is a species of phasmid or stick insect found across North America. The average length of this species is 75mm (3 in) for males and 95mm (3.7 in) for females.
Pteronarcys californica is a species of insect in the family Pteronarcyidae, the giant stoneflies and salmonflies. It is known commonly as a salmonfly. Salmonflies are an important aquatic insect for fly anglers and many nymph and adult fly patterns are tied to imitate this insect.
Ephemera danica, the green drake or green drake mayfly, is a species of mayfly in the genus Ephemera.
Chloroperlidae are a family of stoneflies, commonly known as green stoneflies, with more than 200 species and 22 genera. They appear green to yellow in colour, and are popularly used among fisherman as bait for trout fishing. Green stoneflies live in the benthic zone of the cold streams and rivers of five continents and four zoogeographical regions, emerging from the water to live in the riparian zone as adults. They are sensitive to pollutants, making them an indicator species for determining the quality of water bodies. Chloroperlidae are hemimetabolous, having no pupal stage, but instead hatch from eggs as nymphs and mature directly into adults. They are omnivorous, feeding on small organisms and plant particles, and become more carnivorous as they mature. The classification of Chloroperlidae is contested, with some believing that they should be considered as members of different orders, as opposed to the order Plecoptera that they currently belong to.
Progomphus borealis is a species of dragonfly in the family Gomphidae. This dragonfly species is commonly known as the gray sanddragon.
Gomphurus externus, the plains clubtail, is a species of dragonfly in the family Gomphidae.
Coxoplectoptera or "chimera wings" is an extinct order of stem-group mayflies containing one family, Mickoleitiidae.
Most insects reproduce oviparously, i.e. by laying eggs. The eggs are produced by the female in a pair of ovaries. Sperm, produced by the male in one testis or more commonly two, is transmitted to the female during mating by means of external genitalia. The sperm is stored within the female in one or more spermathecae. At the time of fertilization, the eggs travel along oviducts to be fertilized by the sperm and are then expelled from the body ("laid"), in most cases via an ovipositor.
Behningiidae is a family of mayflies. It is a primitive family; the nymphs burrow in the sediment but lack tusks on their mandibles, and the forelegs are not modified for burrowing. The gills are ventral, and the ones on the first abdominal segment are single and are longer than the gills on the other segments. The forelegs are palp-like and the other two pairs of legs are modified to protect the gills. The family is holarctic in distribution. The genus Dolania occurs in North America and the other three genera occur in northern Europe and Asia.
Ephemera vulgata is a species of mayfly in the genus Ephemera. This mayfly breeds in stationary water in slow rivers and in ponds, the nymphs developing in the mud.
Hexagenia limbata, the giant mayfly, is a species of mayfly in the family Ephemeridae. It is native to North America where it is distributed widely near lakes and slow-moving rivers. The larvae, known as nymphs, are aquatic and burrow in mud and the adult insects have brief lives. They are often referred to as fish flies around the Great Lakes as they tend to cause the areas around water to smell like rotten fish.
Hexagenia bilineata is a species of mayfly in the family Ephemeridae. It is native to North America where it is found in the Upper Mississippi Valley. Sometimes adults of this mayfly are so abundant as to cause a nuisance because of their enormous numbers. The larvae are aquatic and burrow in mud and the adult insects have brief lives.
Leptophlebia marginata, the sepia dun, is a species of mayfly in the family Leptophlebiidae. It is native to Europe and North America where it is distributed widely near lakes, ponds and slow-moving streams. The larvae, which are known as nymphs, are aquatic.
William L. "Bill" Peters (1939–2000) was an American entomologist specializing in mayflies, especially those in the family Leptophlebiidae.
