Aquatic insect

Aquatic insects or water insects live some portion of their life cycle in the water. They feed in the same ways as other insects. Some diving insects, such as predatory diving beetles, can hunt for food underwater where land-living insects cannot compete.


One problem that aquatic insects must overcome is how to get oxygen while they are under water. All animals require a source of oxygen to live. Insects draw air into their bodies through spiracles, holes found along the sides of the abdomen. These spiracles are connected to tracheal tubes where oxygen can be absorbed. All aquatic insects have become adapted to their environment with the specialization of these structures

Aquatic adaptations
  1. Simple diffusion over a relatively thin integument
  2. Temporary use of an air bubble
  3. Extraction of oxygen from water using a plastron or physical gill
  4. Storage of oxygen in hemoglobin molecules in hemolymph
  5. Taking oxygen from surface via breathing tubes (siphons)

The larvae and nymphs of mayflies, dragonflies and stoneflies possess tracheae but when in larval stage the tracheae are connected to gills, which are very thin extensions of the exoskeleton through which oxygen in the water can diffuse.

Some insects have densely packed hairs (setae) around the spiracles that allow air to remain near, while keeping water away from, the body. The trachea open through spiracles into this air film, allowing access to oxygen. In many such cases, when the insect dives into the water, it carries a layer of air over parts of its surface, and breathes using this trapped air bubble until it is depleted, then returns to the surface to repeat the process. Other types of insects have a plastron or physical gill that can be various combinations of hairs, scales, and undulations projecting from the cuticle, which hold a thin layer of air along the outer surface of the body. In these insects, the volume of the film is small enough, and their respiration slow enough, that diffusion from the surrounding water is enough to replenish the oxygen in the pocket of air as fast as it is used. The large proportion of nitrogen in the air dissolves in water slowly and maintains the gas volume, supporting oxygen diffusion. Insects of this type only rarely need to replenish their supply of air.

Other aquatic insects can remain under water for long periods due to high concentrations of hemoglobin in their hemolymph circulating freely within their body. Hemoglobin bonds strongly to oxygen molecules.

A few insects such as water scorpions and mosquito larvae have breathing tubes ("siphons") with the opening surrounded by hydrofuge hairs, allowing them to breathe without having to leave the water.

Orders with aquatic or semiaquatic species


  • Drees, B.M. and Jackman, J. (1999), "Diving Beetle" in Field Guide to Texas Insects, Gulf Publishing Company, Houston, Texas. (Accessed 9 January 2009)
  • Farb, P. (1962). The Water Dwellers [LIFE]INSECTS pg. 142.
  • Meyer, J.R. (2006), "Respiration in Aquatic Insects". (Accessed 25 April 2008)
  • Stanley, D. and Bedick, J. (1997). "Respiration in aquatic insects". (Accessed 27 December 2003)
  • Wigglesworth, Vincent B. Sir (1964). The life of insects. Weidenfeld & Nicolson, London

External links

  • Insect stages - "Some larvae, nymphs and adult insects that live in freshwater." A UK-based web site with microscopic photos of various insects and other microorganisms as well as biological information.
Boulder darter

The boulder darter (Etheostoma wapiti) is a species of ray-finned fish in the perch family. It is endemic to Alabama and Tennessee in the United States, where it occurs in the Elk River system and Shoal Creek. It is found in small rivers and fast-flowing streams, at least 2 ft (0.6 m) deep, with boulders or a rocky base. It feeds on aquatic insect larvae but little is known of its natural history. The population trend of this fish is unknown but it is affected by a rise in siltation and the impoundment of water within its range by the building of dams. The International Union for Conservation of Nature has assessed its conservation status as being "vulnerable".

Bronze-winged duck

The bronze-winged duck (Speculanas specularis) also known as the spectacled duck, is a dabbling duck and the sole member of its genus Speculanas. It is often placed in Anas with most other dabbling ducks, but its closest relative is either the crested duck or the Brazilian duck, which likewise form monotypic genera. Together they belong to a South American lineage which diverged early from the other dabbling ducks and may include the steamer ducks.

Named after the "bronze" speculum this species is also known as "pato perro" or "dog-duck" after the harsh barking call of the female.

The bronze-winged duck lives among forested rivers and fast-flowing streams on the lower slopes of the South American Andes, in central and southern Chile and adjacent parts of Argentina.

The sexes are alike.

As noted by Johnsgard (2010): "Most observers agree that heavily forested rivers that are relatively swift-flowing are the preferred habitat of this species, although they also occur on slow-moving rivers and on pools or ponds of the adjoining forest areas. They are said to consume both vegetable and animal materials, and have been observed eating small snails that abound on stony shingle beaches. Stomach remains from two birds that were examined contained the seeds of water crowfoot (Batrachium), water milfoil (Myriophyllum), and a bulrush, leaves of water crowfoot, foliage and seeds of a pondweed, and caddis fly larvae as well as a few other aquatic insect remains (Phillips, 1922–26). In captivity at least the birds seem to spend a good deal of time on land and have not been observed diving for food."


The Distichodontidae are a family of African freshwater fishes of the order Characiformes.Two evolutionary grades are found in this family; micropredators (predators of very small organisms like aquatic insect larvae) and herbivores have a nonprotractile upper jaw and a deep to shallow body, while carnivores have a movable upper jaw and an elongated body. Although the herbivores primarily feed on plant material, these species often have omnivorous tendencies. The carnivores include specialized fish-eaters (genus Mesoborus), fin-eaters (Belonophago, Eugnathichthys and Phago) and species that will feed on both whole fish and fins (Ichthyborus). The fin-eaters attack other fish, even ones that are much larger, where they bite off pierces of fins with their sharp teeth.The fish in Distichodontidae vary greatly in size among species, with the smallest micropredators being less than 8 cm (3.1 in) in length, and the largest herbivores can reach up to 83 cm (33 in).

Four-spotted chaser

The four-spotted chaser (Libellula quadrimaculata), known in North America as the four-spotted skimmer, is a dragonfly of the family Libellulidae found widely throughout Europe, Asia, and North America.

The adult stage is found between April to early September in the United Kingdom, and from mid-May to mid-August in Ireland. Larvae have a two-year developmental cycle. Adults feed predominantly on mosquitoes, gnats, and midges; the larvae feed primarily on other aquatic insect larvae and on tadpoles.

There is a variant form, praenubila Newman, which has exaggerated wing spots. This is believed to be related to water temperatures during larval development, and appears to be more common in Europe than in the Americas.

The four-spotted skimmer is the state insect of Alaska.

Ghost knifefish

The ghost knifefishes are a family, Apteronotidae, of ray-finned fishes in the order Gymnotiformes. These fish are native to Panama and South America. They inhabit a wide range of freshwater habitats, but more than half the species in the family are found deep in rivers (typically deeper than 5 m or 16 ft) where there is little or no light.They are distinguished from other gymnotiform fishes by the presence of a caudal fin (all other families lack a caudal fin) as well as a fleshy dorsal organ represented by a longitudinal strip along the dorsal midline. They vary greatly in size, ranging from about 15 cm (6 in) in total length in the smallest species to 60 cm (2 ft) in the largest. It has been claimed that Apteronotus magdalenensis is up to 130 cm (4.3 ft), but this is not supported by recent studies, which indicate that it does not surpass about 50 cm (1.6 ft). These nocturnal fish have small eyes. Also, sexual dimorphism exists in some genera in snout shape and jaws.Apteronotids use a high frequency tone-type (also called wave-type) electric organ discharge (EOD) to communicate.Many Apteronotids are aggressive predators of small aquatic insect larvae and fishes, though there are also piscivorous and planktivorous species. Magosternarchus spp. are very unusual, preying on the tails of other electric fishes. Other species, such as Sternarchorhynchus and Sternarchorhamphus, have tubular snouts and forage on the beds of aquatic insect larvae and other small animals which burrow into the river bottom. At least one species (Sternarchogiton nattereri) eats freshwater sponges which grow on submerged trees, stumps, and other woody debris.

The genus Apteronotus is artificial and some of the species do not actually belong in it.

The black ghost knifefish (Apteronotus albifrons) and brown ghost knifefish (Apteronotus leptorhynchus) are readily available as aquarium fish. Others are known to appear in the trade but are quite rare.

Grey crow

The grey crow (Corvus tristis), formerly known as the bare-faced crow, is about the same size (42–45 cm in length) as the Eurasian carrion crow (Corvus corone) but has somewhat different proportions and quite atypical feather pigmentation during the juvenile phase for a member of this genus.

The tail feathers are relatively long and graduated and the legs are relatively short. The overall colouring of the adult bird is black with randomly bleached wing and tail feathers. A large region around the eye is quite bare of feathering and shows pinkish-white skin with the eyes a bluish-white. The bill is unusual too in being very variable, bluish on upper mandible and pinkish-white on the lower in some specimens, while on others the whole bill is pinkish white with a darker tip. The forward pointing nasal bristles so often prominent in other Corvus species are very reduced also.

The juvenile bird by comparison has remarkably pale plumage being light brown to cream, the wings, tail and primaries showing blackish-brown and fawn and the head and underparts often almost white.

The species occurs all over the huge island of New Guinea and associated offshore islands in both primary and secondary forest in both lowland and hill forest up to 1350 m.

Feeding is both on the ground and in trees taking a very wide range of items. Fruit seems to be very important making up a large percentage of the intake though small animals such as frogs and aquatic insect larvae are taken from shallow water on sand or shingle beds in rivers. When foraging through the trees the birds keep loose, noisy contact with each other and usually number between 4–8 individuals.

The voice is described as a weak sounding 'ka' or a whining 'caw' with other hoarse sounding notes added when excited.

Hare's Ear

The Hare's Ear is a traditional artificial fly imitating an aquatic insect larva (nymph) used in fly fishing.

Leptobotia elongata

Leptobotia elongata, the imperial flower loach, elongate loach or royal clown loach, is a species of botiid fish found in flowing water in the upper and middle Yangtze basin in China. It is the largest species in the family, reaching up to 50 cm (1.6 ft) in length and 3 kg (6.6 lb) in weight. Formerly common, the numbers of this vulnerable species have declined because of overfishing, dams (limiting its breeding migration), habitat loss and pollution. A stocking project has been in place since 2010. It is sometimes kept in aquariums, but require a very large tank.Adults migrate upstream to spawn between March to May. They have been recorded feeding on fish, shrimp, gammarids, benthic invertebrates, aquatic insect larvae, mollusks, plankton and phytodetritus. The feeding preference depends on size: Individuals less than 11 cm (4.3 in) long mainly take benthic invertebrates and aquatic insect larvae, while larger individuals mainly feed on fish and shrimp.

Lethocerus patruelis

Lethocerus patruelis is a giant water bug in the family Belostomatidae. It is native to southeastern Europe, through Southwest Asia, to Pakistan, India and Burma. It is the largest European true bug and aquatic insect. Adult females are typically 7–8 cm (2.8–3.1 in) long, while the adult males are 6–7 cm (2.4–2.8 in).


Macrognathus is a genus of eel-like fish of the family Mastacembelidae of the order Synbranchiformes.

These fish are distributed throughout most of South and Southeast Asia. Macrognathus species feed on small aquatic insect larvae as well as oligochaetes.


Megaloptera is an order of insects. It contains the alderflies, dobsonflies and fishflies, and there are about 300 known species.

The order's name comes from Ancient Greek, from mega- (μέγα-) "large" + pteryx (πτέρυξ) "wing", in reference to the large, clumsy wings of these insects. Megaloptera are relatively unknown insects across much of their range, due to the adults' short lives, the aquatic larvae's often-high tolerance of pollution (so they are not often encountered by swimmers etc.), and the generally crepuscular or nocturnal habits. However, in the Americas the dobsonflies are rather well-known, as their males have tusk-like mandibles. These, while formidable in appearance, are relatively harmless to humans and other animals; much like a peacock's feathers, they serve mainly to impress females. However, the mandibles are also used to hold females during mating, and some male dobsonflies spar with each other in courtship displays, trying to flip each other over with their long mandibles. Dobsonfly larvae, commonly called hellgrammites, are often used for angling bait in North America.

The Megaloptera were formerly considered part of a group then called Neuroptera, together with lacewings and snakeflies, but these are now generally considered to be separate orders, with Neuroptera referring to the lacewings and relatives (which were formerly called Planipennia). The former Neuroptera, particularly the lacewing group, are nonetheless very closely related to each other, and the new name for this group is Neuropterida. This is either placed at superorder rank, with the Endopterygota—of which they are part—becoming an unranked clade above it, or the Endopterygota are maintained as a superorder, with an unranked Neuropterida being a part of them. Within the endopterygotes, the closest living relatives of the neuropteridan clade are the beetles.

The Asian dobsonfly Acanthacorydalis fruhstorferi can have a wingspan of up to 21.6 cm (8.5 in), making it the largest aquatic insect in the world by this measurement.

Palingenia longicauda

Palingenia longicauda is an aquatic insect in the order Ephemeroptera. It is known as the Tisa or Tisza mayfly after the European Tisza river where it is found and also as the long-tailed mayfly and giant mayfly since it is the largest mayfly species in Europe, measuring 12 cm (4.7 in) from head to tail.Unlike many other species of mayflies, adult P. longicauda never move away from water; they fly low and their cerci are frequently touching or sweeping the surface. The slow-moving river and absence of surface-feeding fish help make this possible. The presence of P. longicauda is an indicator of clean unpolluted water. Now extinct in many European countries, it can be found in Slovakia, Serbia and Hungary on the Tisza river, as well as in Romania, on the Prut and Bega.

Partridge and Orange

The Partridge and Orange is an artificial fly commonly categorized as a wet fly or soft hackle and is fished under the water surface. The fly is a well known fly with its roots set firmly in English angling history. It is an impressionistic pattern fished successfully during caddis hatches and spinner falls. The Partridge and Orange is traditionally a trout and grayling pattern but may be used for other aquatic insect feeding species.

Pheasant Tail Nymph

The Pheasant Tail is a popular nymph imitation used when fly fishing. It is used to mimic a large variety of aquatic insect larvae that many fish including trout feed upon. It is also widely referred to as the Sawyer’s Pheasant Tail, in relation to the original creator of this fly.


Leaffishes are small fishes of the Polycentridae family. According to FishBase, it only includes the genera Monocirrhus and Polycentrus from fresh and brackish water in tropical South America. Although included in the Asian leaffish family Nandidae by FishBase, most recent authorities place the African Afronandus and Polycentropsis in Polycentridae. Polycentridae were formerly placed in the order Cichliformes but are now regarded as being incertae sedis in the subseries Ovalentaria in the clade Percomorpha.All of these fishes are highly specialized ambush predators that resemble leaves, down to the point that their swimming style resembles a drifting leaf (thus the common name leaf fish); when a prey animal - such as an aquatic insect or smaller fish - comes within range, the fish attacks, swallowing the prey potentially within a quarter of a second. To aid in this lifestyle, all members of the family have large heads, cryptic colors and very large protractile mouths capable of taking prey items nearly as large as they are. These intriguing behaviors have given the family a niche in the aquarium hobby; however, none of these species are easy to maintain in aquariums, requiring very clean, soft, acidic water and copious amounts of live foods.

Rhode Island Department of Environmental Management

The Rhode Island Department of Environmental Management (RIDEM) is a Rhode Island state government agency charged with supervising and controlling the protection, development, planning, and utilization of the natural resources of the state, including, but not limited to: water, plants, trees, soil, clay, sand, gravel, rocks and other minerals, air, mammals, birds, reptiles, amphibians, fish, shellfish, and other forms of aquatic, insect, and animal life.It includes the Division of Parks and Recreation which is responsible for management of Rhode Island's fifteen State Parks, seven state beaches, and five public use lands.


The hymenopteran family Scelionidae is a very large cosmopolitan group (over 3000 described species in some 160 genera) of exclusively parasitoid wasps, mostly small (0.5–10 mm), often black, often highly sculptured, with (typically) elbowed antennae that have a 9- or 10-segmented flagellum. Nowadays, it is considered to be a subfamily of the Platygastridae.

They are generally idiobionts, attacking the eggs of many different types of insects, spiders, butterflies (the hackberry emperor, for example) and many are important in biological control. Several genera are wingless, and a few attack aquatic insect eggs underwater.


Schmutzdecke (German, “dirt cover” or dirty skin, sometimes wrongly spelled schmutzedecke) is a hypogeal biological layer formed on the surface of a slow sand filter. The schmutzdecke is the layer that provides the effective purification in potable water treatment, the underlying sand providing the support medium for this biological treatment layer.

The composition of any particular schmutzdecke varies, but will typically consist of a gelatinous biofilm matrix of bacteria, fungi, protozoa, rotifera and a range of aquatic insect larvae. As a schmutzdecke ages, more algae tend to develop, and larger aquatic organisms may be present including some bryozoa, snails and annelid worms.

Water boatman

Water boatman as a type of aquatic insect can mean:

Arctocorisa arguta, in genus Arctocorisa and subfamily Corixinae, known as water boatmen in New Zealand

Corixa punctata, a species known as the lesser water boatman in the United Kingdom

Corixidae, a family known as water boatmen in the United States and Australia

Notonecta glauca, a species known as the greater water boatman in the United Kingdom (called the backswimmer in the United States)

Sigara, a genus known as water boatmen in New Zealand

Aquatic ecosystems

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