Insects have colonized streams, ponds, and lakes multiple times. Aquatic insects are key players in freshwater ecological communities. Aquatic insects represent a fascinating adaptive radiation of arthropods into freshwater environments. These insects often metamorphose into terrestrial adult, or into an adult that inhabits a different part of the aquatic environment than the immature form.
Order: Ephemeroptera (mayflies)
Ephemeroptera refers to short adult life of insects. These are delicate and slender insects, most of the species live only for a few hour or day. The habitat of nymph is fresh running water of ponds and streams; adult is short lived flying insect.
Mouthparts are chewing and vestigial; antennae are short and setaceousor styliform. Fore wings are large and triangular; hindwings greatly reduced, or even absent. Abdomen ends in very long and many segmented two or three long caudal filaments. The median caudal filament may or may not be present. When present it is like cerci. Sub imaginal molting (the fresh adults shed their wings from their body) in winged sub adults present. The nymphs are called naiads as these are aquatic, distinguished by seven pairs of gills along the abdomen.
Families included are: Ephemeridae (Ephemera sp.), Ephemerellidae (Ephemerella sp.),Baetidae (Baetis sp.), Heptageniidae, and Caenidae (Caenis sp.).
Order: Odonata (dragonflies and damsel flies)
Odonata refers to the mandibles, which are provided with strong teeth in these insects. These are aquatic as nymph and can be found in fresh water streams, ponds, and rivers. As adults they are winged and are successful and important predators.Anisoptera is the sub order of dragonflies and Zygoptera is of damselflies.
These insects have chewing mouthparts and are predaceous in both nymph and adult stages. Their labium is greatly modified into spoon shaped or prehensile organ or a mask for catching prey, brown and green bodies tend to provide camouflage and allow nymph to blend with aquatic habitat of ponds and pond bottoms; antennae are very short and setaceous, compound eyes are very large. Wings are equal in damselflies and sub equal in dragonflies and are greatly veined, with nodeand pterostigma. Legsform a basket below head for catching and eating prey during flight and trochanter is two segmented. Abdomen is thin and long, secondary male genitalia are present on lower side of 2nd abdominal segment.
Families of Anisoptera: Cordulegasteridae(Cordulegaster sp.), Gomphidae (Anarmogomphos sp.), Aeshnidae (Anex sp.), and Libellulidae (Pantala sp.).
Families of Zygoptera: Agrionidae (Agrion sp.), Coenagrionidae (Coenagrion sp.), Lestidae (Lestes sp.), and Chlorocyphidae.
Plecoptera refers to the anal lobe of hind wings, which are folded fan like at rest. The habitat of nymph is cold lakes or fast moving streams; adult is the flying insect and found resting upon stones and tree trunks near the margins of streams and lakes in the mountainous areas.
These have chewing type of mouthparts but vestigial; antennae long and setaceous. Hind wings are larger than fore wings and with well developed foldable anal lobes. Abdomen ends into two long cerci. Nymphs are aquatic, without leaf like gills on abdomen and with two long caudal filaments.
Families included are: Perlidae (Perla sp.), Leptoperlidae (Leptoperla sp.), Capniidae (Capnia sp.), and Nemouridae (Nemoura sp.).
Order:Hemiptera (true bugs)
Hemiptera refers to the front wings in which the basal half is thickened and the apical half is membranous. Its members are found in terrestrial, aquatic, and ectoparasite habitats. Both nymph and adult lives in ponds, slow moving streams and intertidal marshes.
These have piercing-sucking types of mouthparts, with labium modified into sucking proboscis; antennae generally filiform and long. Fore wings are e modified into hemelytra, with basal half is thickened and apical half is membranous, hind wings are membranous throughout and folded under fore wings. These insects have various legs modification for swimming.
This order further classified into two suborders: Cryptocerata (aquatic bugs) andGymnocerata (terrestrial bugs).
Cryptocerataincluded the following families:-
Family: Corixidae (Water boatmen)
Family: Notonectidae (Back swimmers)
Family: Nepidae (Water scorpions)
Family: Belostomatidae (Giant water bug)
Family :Hydrometridae (Water measurer)
Family: Gerridae (Water striders)
Order:Coleoptera (beetles and weevils)
Coleoptera refers to the front wings which act as protective sheath for hind wings, which are folded under them. Their habitat is slow moving streams, decaying organic matter, aquatic and semi-aquatic habitats.
These have chewing type of mouthparts; but in weevils (also known as snout beetles) head is drawn forward to form elongated snout with the mouthparts at the end; antennae are varied types. Forewings are hard, thickened elytra meeting in a straight line on back and hind wings are membranous.
Families of Coleoptera including aquatic insects are:
Trichoptera refers to the dense hair on the wings of most of these insects. The habitat of larvae is streams and ponds; adult are the land dwelling flies.
These are moth like insects with chewing type of mouthparts; with long setaceous antennae and no scales on body. Wings are membranous, hairy, occasionally bear scales and held roof like over the abdomen at rest. ManyCaddisfly larvae can be recognized by soft bodies which are covered by tube like cases that the larvae build from twigs, leaves, grasses and pebbles. Some larvae do not build cases where the current is not so strong such as ponds. They have characteristic motion known as the “Caddisfly Dance”, of wiggling back and forth and up and down. Claspers are well developed at the end of abdomen.
Families included are: Hydrophilidae (Hydroptila), Limnephilidae (rice pests).
Order: Diptera (True flies, midges, mosquitoes and gnats)
Diptera refers to the presence of a pair of front wings in these insects. Their larvae are found in ponds, lakes, marshes, slow moving streams and some species have adapted to fast moving streams; adult are flying insects.
These have sponging, or piercing-sucking, lacerating type, cutting- sponging, or raspingand lapping type; antennae are of varied type. These insects have one pair of membranous wings, the hind pair greatly reduced to knobbed halteres.
Families of Diptera including aquatic insects are:
Family: Tipulidae (Crane flies or Daddy-long legs)
Family: Culicidae (Mosquitoes)
These all organisms are an important component of aquatic food webs because they break down and process organic matter and provide food for invertebrates and vertebrates. The species found in a stream or pond reflect the ecological condition of the aquatic environment some species occur mostly in well aerated ,rushing streams, others favor low oxygen, high nutrient environment. Thus, aquatic insects may be used to identify the water quality of a river or stream.