Aquatic Hexapod Resources

Good sources of help for keying insects to family:
Videos of aquatic invertebrates (and some fish) in action:

    Class Parainsecta, Order Collembola - springtails, snow fleas

    - mouthparts internalized, mandible and maxilla partially contained within head capsule (endognathous)
    - wingless (apterous)
    - metamorphosis - none, ametabolous
    - club-shaped antennae
    - furcula - a forked tail from underside of abdomen when released acts like a spring vaulting the insect into the air for movement
    - collophore - a tube-like projection from lower abdomen thought to aid in water regulation
    - small, usually about 1-2mm, furcula can move them 5-6 cm, body shape either elongate or globular
    - scavengers
    - aquatic species found on the surface of waters (neustonic); most terrestrial, found in moist soils among humus and other debris

    Checklist of the Collembola:

    *Class Insecta - true insects

    *Order Ephemeroptera - mayflies

    - gills on abdomen, including mid-abdominal segments, often plate-like
    - hemimetabolous (egg, larva and adult); adult short-lived, often just a day or so
    - adult with a pre-reproductive (subimago or dun) stage, which soon again molts into a reproductive adult (imago or spinner)
    - 1 tarsal claw
    - usually 3 cerci, though middle segment may be reduced or absent in some genera
    - mostly are primary consumers, but some are carnivorous
    - usually intolerant of poor water quality

    *Order Odonata - dragon- and damselflies
Anisoptera, Dragonflies(c) 1998, Ethan Bright Adult (c) Mark O'Brien
    - gills as mentioned below
    - hemimetabolous, both larvae and adult carnivores; adult strong, agile fliers
    - larvae with enlarged lower mouth that can extend outwards to capture prey (gape limited predator)
    - two suborders in Michigan
       Suborder Zygoptera - damselflies
            - nymph slender, thorax and abdomen not wider than head
            - 3 slender caudal lamella (gills) at end of abdomen
            - adults hold wings up
            - Common families: Coenagrionidae, Lestidae, Calopterygidae
       Suborder Anisoptera - dragonflies
            - nymph robust, thorax and/or abdomen wider than head
            - no caudal gills, rather gills contained within rectal chamber in abdomen
            - adults hold wing outwards from body
            - Common families: Aeshnidae, Cordulegastridae, Macromiidae, Corduliidae, Libellulidae

        more about Odonata:
                    detailed list of links:

    Division Neoptera - insects that fold wings behind back

    *Order Plecoptera - stoneflies

    - hemimetabolous, adult similar to nymph
    - with or without gills, but gills never on middle abdominal segments
    - various trophic levels, scrapers and grazers of algae, shredders, predators
    - generally found in clear, cold streams, often with lots of cobble, usually very intolerant of poor water quality
    - 2 tarsal claws
    - 2 cerci

    *Order Hemiptera (true bugs) = Order Heteroptera
Belastomatidae, Giant Water Bugs© Biodidac  Corixidae, Water Boatmen Photograph by E. Dunbar
Gerridae, Water StridersPhotograph by E. Dunbar

    - hemimetabolous (paurametabolous - nymph very similar to adult, with gradual change to mature adult stage)
    - functional wings - front half of fore wing hardened
    - many hold air supply in "air bubble" under wing, others use "siphon" to breath air directly from atmosphere
    - most predacious, some genera in family Corixidae often detritivores, algivores as well as predators
    - have a "beak," piercing-sucking mouthparts which they dump digestive fluid into prey and suck it back out
    - 2 tarsal claws
    - Common families: Corixidae, Belostomatidae, Nepidae, Gerridae, Notonectidae

    - insects with wing sheaths developing within body; holometabolous (egg, larva, pupa, adult)

    Order Neuroptera - spongillaflies

    - larvae found associated with freshwater sponges (Spongillidae)
    - piercing mouthparts
    - holometabolous
    - One family: Sisyridae

    *Order Megaloptera - dobson- and alderflies
©1997 Thomas Ames Jr.Sialis larva : source >>
    - predacious, with large mandibles, larger individuals will deliver an extremely PAINFUL BITE; adults do not feed
    - holometabolous, only larvae are aquatic, larval crawls out of water to construct terrestrial puparium
    - sexual dimorphism in adults, males with large tusks
    - multi-segmented antennae
    - tarsus with 2 claws
    - abdomen ending with 2 prolegs, 2 claws each (dobsonfly) or a single long filament (alderfly)
    - eggs laid under alder leaves (looks like bird poop)

    *Order Coleoptera - beetles

    - holometabolous, various stages aquatic or terrestrial (very diverse)
    - larvae may look like caddisfly or alderfly larvae, but have NO anal claw, and only 1 claw per tarsus
    - multi-segmented antennae
    - some larvae with large mandibles that WILL BITE
    - predators (large dytiscid or hydophilid larvae will feed on large insects, small fish and tadpoles), but
      some are scrapers (Elmidae, Psephenidae)
    - Common families: Dytiscidae, Hydrophilidae, Elmidae, Psephenidae, Gyrinidae

  *Order Trichoptera - caddisflies

    - holometabolous, egg, larvae and pupae are aquatic
    - larvae often build cases or nets, in which they often pupate
    - scleritization on pro-, head, meso- and metathorax, rest of body soft
    - antennae on larvae very small (usually just small bumps), but very long on adults
    - adults often mistaken for moths, but trichopteran adults have mouth parts reduced or vestigal (not
      prehensile), have hairs on their wings (not scales like moths), and hold wings up tent-like (upright and
      together like moths), and have cerci
    - larvae have anal claws at end of abdomen
    - usually intolerant of very poor water quality
    - most are primary consumers, shredders, some are carnivores and frequently omnivores
    - various genera often characteristic of either lentic or lotic, warm and cold water systems
    - Common families: Hydropsychidae, Philopotamidae, Hydroptilidae, Limnephilidae, Glossomatidae,
      Brachycentridae, Phryganeidae

    Order Lepidoptera - moths and butterflies
source of picture: >>

    - holometabolous, egg, larvae and pupae usually aquatic
    - no cerci or chewing mouthparts in adults like trichopterans
    - larvae with 3-6 prolets ringed with fine hooks on abdominal segments
    - one common family in Michigan in freshwaters - Pyralidae

    *Order Diptera - true flies

    (Tabanidae; Dixidae; Ptychopteridae; Chaoboridae) source of picture:

    - holometabolous, egg, larvae and pupae are aquatic
    - adults with only 1 pair of legs, metathorax with club like balancing structure (halteres)
    - thorax without segmented legs
    - prolegs, pseudopods, and creeping welts are frequent structures on larval body
    - larvae with almost no sclerotization
    - usually primary consumers, but some are also detritivores, shredders and predators
    - four very common dipteran families in Michigan freshwaters:

            - Family Chironomidae - non-biting midges

                - larvae usually white, or clear, but some with hemoglobin and appear red (blood midges)
                - head capsule scleritized, body soft
                - thoracic and anal prolegs
                - adult looks similar to mosquito
                - most speciose family of aquatic insects (20,000 species?), often most numerous single
                  type of aquatic insects, hence often plays an extremely important role in food chains
                - primary consumers (algae), shredders, detritivores, carnivores

            - Family Tipulidae - crane flies

                - larvae worm- or maggot-like
                - tiny head retracted into thorax
                - adults have long wings and legs ("daddy long legs mosquito")
                - largest dipteran family, most species are terrestrial but many aquatic genera
                - shredders, carnivores

            - Family Simulidae - black flies

                - larvae "bulb-shaped" with sclerotized head
                - thorax with large proleg
                - head with large fans that allow filter-feeding of algae, usually lotic waters
                - adults often require blood meal, can emerge in huge numbers
                - associated with some diseases in Africa

            - Family Culicidae - mosquitos

                - larvae have anal syphon for breathing atmospheric air
                - head is distinct from segmented body
                - filter feeders
                - lentic waters of many types, can occur in high densities, do not do well in moving waters
                - adults often require blood meal, often associated with many diseases worldwide