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Macroinvertebrate Photographs and Descriptions
Developed by Big Sandy Resource Conservation and Development Area Courtesy of the U.S. Environmental Protection Agency, the Kentucky Division of Water, and the Mountain Association for Community Economic Development WEF_Macroinvertibrates
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Aquatic Worms Water Quality Indicators of Poor Water Quality (Group Three)
They are either red, brown, or black They have a circular, thin, segmented body They can possibly be up to five inches They often have short bristles or hairs that help them move (They are usually not visible to the human eye) Measure 1 to 30 mm in length, but sometimes over 100 mm Clear whitish to pink in color Body consists of 7 to 500 segments Segments often have bristles or hairs Tolerant of low dissolved oxygen concentrations Found in silty substrates and among debris or detritus in ponds, lakes, streams and rivers Dense populations of aquatic worms can often be found in organically polluted rivers Approximately 200 species in North America Aquatic Earthworm Aquatic Earthworm WEF_Macroinvertibrates
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Leeches Indicators of Poor Water Quality (Group Three)
Measures 1.0 mm to 5.0 cm in length Typically flattened from the back to the belly Always have 34 segments Suckers at both ends Leeches are common in warm protected waters of lakes, ponds, streams, and marshes. Leeches usually avoid light by hiding under rocks or among aquatic vegetation or detritus Silty substrates are unsuitable for leeches because they cannot attach properly WEF_Macroinvertibrates
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Midgeflies Indicators of Poor Water Quality (Group Three)
Midgefly Larvae Midgefly Larvae Midgefly Larvae Midge Larvae Measures up to ½ inch in length Body small, cylindrical, and slightly curved Occasionally deep red in color, otherwise variously colored Two small prolegs just posterior to head Frequently found in bottom sediments of lakes, streams, and ponds where they feed on deposited organic material WEF_Macroinvertibrates
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Pouch Snails Indicators of Poor Water Quality (Group Three)
Shell opens to the left Presence of a fleshy “foot” indicates the snail is alive Snails in this category can be distinguished from “other snails” by the opening of the shell To identify a snail, hold it with the tip of the shell pointed up and the opening facing you (as pictured). If the opening is to the left side, you have a pouch snail Do not count empty shells Pouch Snail WEF_Macroinvertibrates
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Other Snails (Including Gilled) Indicators of Poor Water Quality (Group Three)
Other snails (Class Gastropada) Shell opens to the right On most, a covering, called the operculum, indicates the snail is alive; If no operculum is present look for a fleshy “foot” Snails in this category can be distinguished from pouch snails by the opening of the shell To identify a snail, hold it with the tip of the shell pointed up and the opening facing you (as pictured); If the opening is to the right side, you have a snail that falls in the “other snails” category, also referred to as “gill-breathing” snails Note: The flat, coiled snails also fall into this group Do not count empty shells WEF_Macroinvertibrates
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Blackflies Indicators of Poor Water Quality (Group Three)
Blackfly Larvae Measure to ½ inch in length Body cylindrical and widest at the posterior Abdomen terminates in an attachment disc Head usually possesses fan-like appendages Blackfly larvae prefer cold running water and are usually found attached by the end of their abdomens to rocks, woody debris, or vegetation in the currents of rivers and streams WEF_Macroinvertibrates
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Aquatic Beetle Indicators of Moderate Water Quality (Group Two)
Head more slender than that of the dobsonfly 6 legs Some with lateral appendages Size range: ½” – 1” Beetle larvae look somewhat similar to dobsonfly larvae, but are generally smaller in color and more slender and tapered that the dobsonfly larvae Often the head is darker in color than the rest of the body Beetle larvae will not have pronounced pincers that the dobsonfly larvae possess The appendages on the back section (abdomen) of this organism, if present are called “lateral appendages” and should not be mistaken for legs Water Beetle Beetle Larva WEF_Macroinvertibrates
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Craneflies Indicators of Moderate Water Quality (Group Two)
Cranefly Larva Measure 1/3 to 2 inches in length Plump caterpillar-like segmented body Head is usually retracted into the body Milky green to brown color Four finger-like lobes at back end of body Cranefly Larvae Cranefly Larva WEF_Macroinvertibrates
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Damselflies Indicators of Moderate Water Quality (Group Two)
Damselfly Nymph Measures between 0.5 to 2.0 inches in length Nymph has large eyes, (or larva) two pairs of wing pads and a large round or oval abdomen Abdomen terminates in three small pointed gills Can be readily distinguished from other species by the presence of a large jaw, which is modified for grasping and covers the underside of the head Prefers still water, often found among vegetation and leaf packs Damselfly Nymph Damselfly Larvae WEF_Macroinvertibrates
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Crayfish Indicators of Moderate Water Quality (Group Two)
Measures up to 6 inches in length Has 5 pairs of walking legs, the first pair with large pinchers Resembles a small lobster Some crayfish are usually active only at night During the day they hide in burrows or under rocks Crayfish are omnivorous, eating both plants and animals Decapoda (Crayfish) WEF_Macroinvertibrates
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Fishflies Indicators of Moderate Water Quality (Group Two)
Mouth has large, chewing pinchers Retractable breathing tubes extend from top of abdomen (not visible without magnification) Smooth underside Abdominal segments with many strand-like appendages extending from each side Three pairs of legs on middle section of body with tiny pinchers at the end of each Back end is forked with two short tails and two hooks on each tail Light colored Often confused with hellgramite (dobson fly larva) but does not have fluffy gills on underside Fishfly Adult Fishfly WEF_Macroinvertibrates
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Sowbug Indicators of Moderate Water Quality (Group Two)
Sowbug (Class Crustacea, Order Isopoda) Segmented flat body Many legs Dimension range: ¼” to ½” Sowbugs are gray and segmented with an “armored” appearance They look very similar to terrestrial sowbugs, also known as pill bugs They have a sort of rectangular shape and many small legs Sowbugs are most easily found along the stream’s edge WEF_Macroinvertibrates
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Scuds Indicators of Moderate Water Quality (Group Two)
Measures 5 to 20 mm in length Clear whitish to pink in color Laterally flattened (top to bottom) Seven pairs of legs, the first two are modified for grasping Found in shallow freshwater springs, streams, lakes and ponds Most species feed on debris Scuds are an important food source for many fishes WEF_Macroinvertibrates
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Dragonfly Indicators of Moderate Water Quality (Group Two)
Measures between 0.5 to 3.0 inches in length Large eyes Two pairs of wing pads Large round or oval abdomen Abdomen terminates in three small pointed structures Can be readily distinguished from other species by the presence of a large jaw which is modified for grasping and covers the underside of the head Prefer still water, often found among vegetation and leaf packs or burrowed in sediment Dragonfly Larva WEF_Macroinvertibrates
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Dobsonflies Indicators of Good Water Quality (Group One)
Commonly called hellgrammites Measures ¾ to 4 inches in length Body is elongate and somewhat flattened Large pinching jaws Lateral appendages along the length of the abdomen Cotton-like gill tufts on underside of abdomen Abdomen terminates in two small prolegs, each bearing two claws Short inconspicuous antennae Feed on other aquatic insects Usually found on the underside of large rocks in cool, slow-moving streams Handle hellgrammites carefully, larger individuals may deliver a painful pinch! Close-up of Dobsonfly Larvae Mandables Dobsonfly Adult WEF_Macroinvertibrates
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Alderfly Indicators of Good Water Quality (Group One)
Measure to 1 inch in length (including tail) Abdomen terminates in a single tail Lateral filaments along abdomen Often pale to deep reddish-brown in color Alderfly Larva Alderfly Adult WEF_Macroinvertibrates
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Caddisflies Indicators of Good Water Quality (Group One)
Up to 1½ inches 6 hooked legs on upper third of body 2 hooks at back end May be in stick, rock or leaf case with it’s head sticking out May have fluffy gill tufts on lower half Caddisfly Larva Caddisfly Larva WEF_Macroinvertibrates
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Water Penny Indicators of Good Water Quality (Group One)
Measures ¼ inch in length Flat disk-like body Head and legs concealed from above 6 legs and branched gills on underside Water pennies prefer cold, fast moving streams Their smooth, flattened bodies enable them to resist the pull of the current Water pennies are usually found on smooth rocks where they graze on attached algae Water Penny Larvae Water Penny Larvae WEF_Macroinvertibrates
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Clams Indicators of Good Water Quality (Group One)
Fleshy “foot” (not visible if shells are closed tightly) Size range: 1/8” to 5” Clams are easily identified by their two shells, which they will draw tightly closed when handled Count only whole, live clams (those with both shells) in your assessment Please do not force the shells open to see if you have a live clam; If the shell is tightly closed, you can assume the organism is alive Note: Clams are usually buried in the stream bottom, so you should kick up the sampling area thoroughly; Also, as indicated by the size range, clams can be quite small and fragile, so look carefully and handle carefully Do not count empty shells Many clams are endangered so immediately return to the stream where you found them Piston Grip Pond Mussel Fanshell WEF_Macroinvertibrates
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Gilled Snails Indicators of Good Water Quality (Group One)
Up to ¾ inches long Shell opening covered by a thin plate called an operculum With helix pointed up shell opens to right Intolerant of pollution Snails in this category can be distinguished from pouch snails by opening the shell; To identify a snail, hold it with the tip of the shell pointed up and the opening facing you If the opening is on the right side, you have a snail that falls in the “other snails” category, also referred to as the “gill breathing” snails Note: The flat, coiled snails also fall into this group Do not count empty shells WEF_Macroinvertibrates
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Mayflies Indicators of Good Water Quality (Group One)
Mature larvae measure to ¼ to 2 inches in length (excluding tails) Two rows of long hairs present on inside of front legs 2 or 3 tails Slender antennae The conspicuous hairs growing on the inner front legs are used for filtering food particles from the water Brush-legged mayflies may be minnow like with a vertically oriented head and three tails (as pictured) or may be more flattened with a horizontally oriented head and two tails Mayfly Adult Brush-Legged Mayfly Nymph Mayfly Nymph WEF_Macroinvertibrates
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Riffle Beetles Indicators of Good Water Quality (Group One)
Riffle beetles measure approximately 1/16 to 1/4 inch in length Body small, adults usually oval Legs are long Antennae are usually slender Riffle beetles walk slowly underwater; they do not swim on the surface Riffle Beetle Adult Riffle Beetle Adult Riffle Beetle Larvae and Adults WEF_Macroinvertibrates
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Stonefly Indicators of Good Water Quality (Group One)
Measure 8 to 15 mm in length (not including tails) 2 tails 2 sets of wing pads Sometimes have branched gills between legs on underside of body Yellow to brown in color; often patterned yellow and brown when mature Superficially similar to certain flattened mayfly nymphs, however stonefly nymphs always have two tails, prominent antennae, and two claws at the end of each leg Stoneflies are not tolerant to low levels of dissolved oxygen and therefore prefer cold, swift-moving streams; The streamlined, flattened bodies of stonefly nymphs enable them to move about the rocky streambed in rapid currents Stonefly Nymph Stonefly Nymph Stonefly WEF_Macroinvertibrates
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Watersnipe Indicators of Good Water Quality (Group One)
Watersnipe Larvae Measure 12 to 18 mm in length Color varies from pale to green Abdomen has well-developed pairs of ventral prolegs and short dorsal and lateral filaments Posterior pair of processes Widespread in well oxygenated streams and rivers; Some species burrow in soft sediments Carnivorous Watersnip Larva WEF_Macroinvertibrates
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