*Superclass Hexapoda
    - tagmosis - clearly defined body sections of head, thorax, and abdomen
    - mandibles, maxilla and labium
    - thorax with three segments, each bearing one pair of legs

Below is a hypothesized phylogeny of the hexapods that have aquatic groups. You do not need to
memorize this phylogeny, but it is to show that "aquatic insects" are in fact a diverse group of
organisms. These groups are believed to have secondarily invaded freshwater environments from
their terrestrial ancestors - in fact, almost all of these organisms breath atmospheric oxygen during at
least one stage or more of their life history. Many different strategies towards surviving in water
have been developed, especially in terms of respiration, feeding habitats, life stage, behaviors, etc.

Hexapoda                                                                               Order
|
|-----Class and Order Collembola (mouthparts partially internalized)--------*Collembola (springtails)
|
|-----Class Insecta (mouthparts well developed)
        |
        |---Division (and order) Ephemeroptera-----------------------------------------*Ephemeroptera (mayflies)
        |---Division (and order) Odonata---------------------------------------------------*Odonata (dragon- & damselflies)
        |                                                                                                  |-----Zygoptera (damselflies)
        |                                                                                                  |---|
        |                                                                                                      |--Anisozygoptera (not in Michigan)
        |                                                                                                      |--Anisoptera (dragonflies)
        |
        |----Division Neoptera (folds wings behind back, wings maybe secondarily lost)
                |
                |-----?plecopteroid assemblage--------------------------------------------*Plecoptera (stoneflies)
                |-----hemipteran assemblage (Subdivision Paraneoptera)
                |            |
                |            |------Hemiptera (true bugs) (piercing-sucking mouthparts)
                |                        |---other hemipterans
                |                        |--------------------------------------------------------------*Heteroptera
                |                                                                                          |---Gerrimorpha
                |                                                                                          |---Nepomorpha
                |
                |----Subdivision Endopterygota - wing sheaths develop within body of pupa, holometabolous life cycle
                            |
                            |                                                        |------------------Neuroptera (spongillaflies)
                            |                                        |---------------|
                            |----------------------------------------|               |------------------*Megaloptera (dobson-, alder- & fishflies)
                            |                                        |
                            |                                        |----------------------------------*Coleoptera (beetles)
                            |
                            |
                            |                               |-------------------------------------------Hymenoptera (wasps)
                            |                               |
                            |-------------------------------|
                                                            |                             |-------------*Trichoptera (caddisflies)
                                                            |   |-------------------------|
                                                            |---|                         |-------------Lepidoptera (moths & butterflies)
                                                                |
                                                                |---------------------------------------*Diptera (true flies)
 

    *Class and 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 -->http://www.geocities.com/~fransjanssens/

    *Class Insecta - true insects
    *Division and 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

    *Division and Order Odonata - dragon- and damselflies
(c) 1998, Ethan Bright  (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: http://www.capecod.net:80/~bnikula/on4.htm
                    systematics: http://phylogeny.arizona.edu/tree/eukaryotes/animals/arthropoda/hexapoda/odonata/odonata.html


    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

    *Superorder Hemiptera (true bugs) - Order Heteroptera
©Biodidac  Photograph by E. Dunbar
Photograph 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
    - WILL BITE
    - 2 tarsal claws
    - Common families: Corixidae, Belostomatidae, Nepidae, Gerridae, Notonectidae


    Endopterygota
    - 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 >>http://140.211.62.101/aquaticinsects/aqinsect.html
    - 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: >>http://www.lcra.org/lands/watershedmanagement/arcbmlis.htm

    - 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


    *Diptera - true flies


    (Tabanidae; Dixidae; Ptychopteridae; Chaoboridae) source of picture: http://140.211.62.101/aquaticinsects/aqinsect.html

    - 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:

            - Chironomidae - non-miting 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

            - 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

            - 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

            - 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