True BugOrder: HemipteraMaximum size: Up to 150 mmDescription: True bugs havepiercing mouth parts and canvary in shape from elongatedand boat-shaped to leaf-like.Habitat: Found among plants,on the water surface, orswimming freely in still toslow-moving waters.

MothOrder: LepidopteraMaximum size: Up to 20 mmDescription: Moths have fleshybodies, often covered with simpleor multiple branched gills, andhave a hard-shelled head. Theybuild portable cases with plantmaterial or permanent silk cases attached to rocks.Habitat: Found among plants inslow-moving waters and on rocksin fast-moving waters.

Water Slater or Sow BugOrder: IsopodaMaximum size: Up to 20 mmDescription: Water slaters orsow bugs are flattened from top to bottom and resemble the garden slater.Habitat: Found in still to slow-moving waters.

Dragonfly andDamselfly Nymph Order: OdonataMaximum size: Up to 50 mmDescription: Dragonfly anddamselfly nymphs haveextendable mouth parts.Dragonfly nymphs have astocky build. Damselflynymphs are narrow andelongated with three gill structures extendingfrom the tail.Habitat: Found on plants,among rocks and leaflitter or burrowing into thesediments of the streambed, in a variety of flowconditions.

Side Swimmer or ScudOrder: AmphipodaMaximum size: Up to 25 mm Description: Side swimmers or scuds haveshort and narrow bodies. They have sevenpairs of walking legs, three small featheryswimming legs and two pairs of antennae.Habitat: Found in still to slow-movingwaters.

Freshwater Mussel Class: BivalviaMaximum size: Up to 180 mmDescription: Freshwater musselshave paired hard shells (valves)with a fleshy body between them.Habitat: Found in or on sandy ormuddy stream beds.

Nematode Phylum: NematodaMaximum size: Up to 4 mm Description: Nematodes are very small, pale worms withoutsegments and can look translucent.Habitat: Found anywhere withsufficient moisture.

Fly LarvaOrder: DipteraMaximum size: Up to 30 mmDescription: Fly larvae varyconsiderably in body structure.Larvae are usually thin andelongated with stubby legs or no legs.Habitat: Foundswimmingfreely, or living onrocks, plants and inthe stream bed, ina variety of flowconditions.

tolerant3

3

3

3

very tolerantFlatwormClass: TurbellariaMaximum size: Up to 20 mmDescription: Flatworms are flat,thin, slow-moving worms withtwo simple eye spots.Habitat: Found gliding overrocks, wood and other parts of the stream bed, in a variety of flow conditions.

Segmented WormClass: OligochaetaMaximum size: Up to 30 mm Description: Segmented wormslook like ordinary earthwormsbut are thinner and smaller.Habitat: Found in soft sediment,rich in organic matter.

HydraClass: HydrozoaMaximum size: Up to 30 mm Description: Hydras have asimple sack-like body with amouth encircled by tentacles.Habitat: Found attached to rocks, plants or wood,often in colonies.

LeechClass: HirudineaMaximum size: Up to 20 mmDescription: Leeches are soft-bodied animals madeup of 32 segments with asucker on one or both ends.Habitat: Found swimmingin the water, on plants orthe stream bed, in avariety of flow conditions.

Freshwater SnailClass: GastropodaMaximum size: Up to 25 mmDescription: Snails are soft-bodied animals enclosed ina hard, protective, coiled shell.Habitat: Found on plants androcks, in a variety of flowconditions.

Moth

Water Slater or Sow Bug

Needle Bug

2

2

2

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1

1

1

2

3

2

Nematode

280270

260250

240230

220210

200290

180170

160150

140130

120110

100190

8070

6050

4030

2010

mm

90

Water Strider

Backswimmer

Water Scorpion

DragonflyNymph

Side Swimmeror Scud

Freshwater Mussel

Water Treader

DragonflyNymph

DamselflyNymph

Bug value

DamselflyNymph

Black FlyLarva

Segmented Worm

Hydra

Freshwater Snail

Bloodworm

MosquitoLarva

Flatworm

Leech

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Water MiteOrder: AcarinaMaximum size: Up to 5 mmDescription: Mites usually havesimple rounded bodies witheight legs.Habitat: Found among plants, or on the stream bed, in slow-moving waters.

BeetleOrder: ColeopteraMaximum size: Up to 35 mmDescription: Adult aquaticbeetles look similar toterrestrial beetles, witha hard-shelled body anda streamlined shape.Aquatic beetle larvae lookvery different from adultsand can vary widely inappearance. Larvae areusually elongated withwell-developed legs.Habitat: Found swimmingin water at all levels,including the surface, orliving on the stream bed, in avariety of flow conditions.

Freshwater Shrimp, Prawn,Yabbie and Crayfish Order: DecapodaMaximum size: Up to 400 mmDescription:This group is distinguished by having10 legs and stalked eyes. Crayfish andyabbies have two robust clawsextending from the body.Habitat: Shrimps and prawns arefound amongst plants and rocks.Yabbies and crayfish burrowamongstrocks,wood,leaflitterand intothe streambed. This groupis often found inslow-moving waters.

Stonefly NymphOrder: PlecopteraMaximum size: Up to 60 mm Description: Stonefly nymphshave long antennae and twothin tails. They often have gillsextending from their rear endsbetween the tails.Habitat: Found among rocks orplants, in fast-moving waters.

Mayfly NymphOrder: EphemeropteraMaximum size: Up to 25 mmDescription: Mayfly nymphshave short antennae and three long thin tails.They usually have gills along the sides of their bodies.Habitat: Found on or underrocks or among plants and leaflitter, in a variety of flowconditions.

Alderfly and Dobsonfly LarvaOrder: MegalopteraMaximum size: Up to 30 mmDescription: Alderfly anddobsonfly larvae are robustanimals with a hard-shelledhead. Their bodies are fleshywith long extensions oneither side.Habitat: Found among rocks, in a variety of flowconditions.

Caddisfly Larva Order: TrichopteraMaximum size: Up to 25 mmDescription: Caddisfly larvaelook like caterpillars and oftenbuild portable cases from fine sand grains, small sticks,leaves, silk and algae. They canalso be caseless.Habitat: Found among rocks,plants, wood and leaf litter,in a variety of flow conditions.

Freshwater macroinvertebrates or ‘water bugs’ areanimals that spend all or part of their lives in thewater – streams, rivers, ponds, wetlands and drains.They are large enough to be seen without the aid ofa microscope or magnifying glass and have nobackbone.

To assist with environmental monitoring, water bugshave been rated from 1 to 10 according to theirsensitivity to pollution. They are grouped into fourcategories. The more sensitive a water bug is tocommon types of pollution, the higher the numberassigned to it. The four categories are:

• very sensitive [10, 9 and 8]

• sensitive [6, 5 and 4]

• tolerant [3]

• very tolerant [2 and 1]

It is important to note that water bugs vary in sizedepending on their species and stage ofdevelopment. The water bugs that you collect maytherefore be smaller than the maximum size used inthis guide.

The colour of the water bugs may also vary.

For information on how to do a water bug surveyvisit www.streamwatch.org.au

2 1

3

6 5 4

10 9 8

Caddisfly Larvae(caseless)

Caddisfly Larvae(caseless)

10

9

8

8

sensitive

Whirligig Beetle(adult)

Whirligig Beetle (larva)

6

5

4

Bug Value

ReferencesChessman, B. (2003). SIGNAL 2 - A Scoring System for Macro-invertebrate(‘Water Bugs’) in Australian Rivers. Monitoring River Health InitiativeTechnical Report No. 31. Commonwealth of Australia, Canberra.Gooderham, J. & Tsyrlin, E. (2002). The Waterbug Book: A Guide to theFreshwater Macroinvertebrates of Temperate Australia. CSIRO Publishing,Victoria, Australia.Hawking, J.H. & Smith, F.J. (1997). Colour Guide to Invertebrates ofAustralian Inland Waters Identification Guide No. 8. Co-operativeResearch Centre for Freshwater Ecology, Murray-Darling FreshwaterResearch Centre, Albury, Australia.Williams, W.D. (1980). Australian Freshwater Life: The Invertebrates ofAustralian Inland Waters. 2nd edn. Macmillan Publishers, Australia.

SW 15 11/05

Water Penny

Diving Beetle (adult)

Bug value

Alderfly Larva

Diving Beetle (larva)

Shrimp

Water Mite

Caddisfly Larvae(cased)

Printed on recycled paper

Stonefly Nymph

Mayfly Nymph

very sensitiveStreamwatchWater Bug Guide

Mayfly Nymph

Dobsonfly Larva

Caddisfly Larvae(cased)

Freshwater Yabbie

STREAMWATCH