order
![](/images/illustrations/illustration_coleoptera_adult_v_160.png)
Coleoptera
“Adult Beetles”
![](/images/illustrations/illustration_coleoptera_larva_v_160.png)
Coleoptera
“Larval Beetles”
![](/images/illustrations/illustration_diptera_larva_v_160.png)
Diptera
“True Flies”
![](/images/illustrations/illustration_ephemeroptera_larva_v_160.png)
Ephemeroptera
“Mayflies”
![](/images/illustrations/illustration_hemiptera_adult_v_160.png)
Hemiptera
“True Bugs”
![](/images/illustrations/illustration_lepidoptera_larva_v_160.png)
Lepidoptera
“Aquatic Caterpillars, Snout Moths”
![](/images/illustrations/illustration_megaloptera_larva_v_160.png)
Megaloptera
“Alderflies, Dobsonflies, and Fishflies”
![](/images/illustrations/illustration_odonata_larva_v_160.png)
Odonata
“Dragonflies and Damselflies”
![](/images/illustrations/illustration_plecoptera_larva_v_160.png)
Plecoptera
“Stoneflies”
![](/images/illustrations/illustration_trichoptera_larva_v_160.png)
Trichoptera
“Caddisflies”
family
Ephemeridae
“Burrowing Mayflies”
Genus Overview
There are at least 7 species of this genus in North America, of which Hexagenia limbata is the most widespread and most famous among fly fishers, who eagerly anticipate a large "Hex hatch" of subimagoes ("duns") in lotic-depositional stretches of rivers and lakes with the appropriate marl substrate. The consistency of the sand-silt marl must be loose enough for larvae to burrow but dense enough for the walls of the burrow not to collapse. Undulation of a larva's body and the feathery gills on its back moves oxygenated water and fine particles of food through the U-shaped burrow. The food is gathered from the sides of the burrow or filtered from the water.
Characteristics
POLLUTION TOLERANCE
Southeast: 4.7 and higher
Upper Midwest: 6 and higher
Midwest: 3.1 and higher
Mid-Atlantic: 6 and higher
0 = least tolerant, 10 = most tolerant
FEEDING HABITS
Collector / Filterer
Collector / Gatherer
Collector / Gatherer
MOVEMENT
Burrower
DISTRIBUTION
Widespread (east of the Rocky Mtns.)
HABITAT
Lentic-littoral
Lotic-depositional
Lotic-depositional
Diagnostic Characters
order
![](https://static.macroinvertebrates.org/gigapans/198003/images.25b802990e2c2dcdf8ea29eb3fd41e2f/198003-120x120-26729-37338-9071-19680.jpg)
Abdominal Gills
![](https://static.macroinvertebrates.org/gigapans/198003/images.25b802990e2c2dcdf8ea29eb3fd41e2f/198003-120x120-15965-17224-5720-6980.jpg)
Single Tarsal Claw
![](https://static.macroinvertebrates.org/gigapans/198003/images.25b802990e2c2dcdf8ea29eb3fd41e2f/198003-120x120-41989-55745-3849-17605.jpg)
Usually 3 Tails
family
![](https://static.macroinvertebrates.org/gigapans/198003/images.25b802990e2c2dcdf8ea29eb3fd41e2f/198003-120x120-26409-36185-9281-19057.jpg)
Fluffy Abdominal Gills
![](https://static.macroinvertebrates.org/gigapans/198003/images.25b802990e2c2dcdf8ea29eb3fd41e2f/198003-120x120-11520-14637-18798-21915.jpg)
Fossorial Foretibiae
![](https://static.macroinvertebrates.org/gigapans/198003/images.25b802990e2c2dcdf8ea29eb3fd41e2f/198003-120x120-5830-9698-11564-15433.jpg)
Large Tusks
![](https://static.macroinvertebrates.org/gigapans/198003/images.25b802990e2c2dcdf8ea29eb3fd41e2f/198003-120x120-24574-27401-17686-20513.jpg)
Pointed Hind Tibiae
+ Expanded Character List
Order:
Wings developing in wing pads. Mouthparts suitable for chewing. Gills present on tops and sides of abdomen. Segmented legs present. One tarsal claw per leg. Usually with 3 tails (sometimes 2).
Family:
Large tusks project forward anteriorly from the face and are visible dorsally, when viewed laterally they curve upward. Foretibiae are fossorial (modified for burrowing: expanded or with tubercles). Ventral apex of each hind tibia acutely pointed. Abdominal gills on segments 2–7 are conspicuous dorsally, forked and elongate-lancolate, with fringed margins, giving the animal a fluffy appearance.
Genus:
Frontal process of head rounded or truncate, never forked or pointed. Most antennal segments with whorls of setae, much longer than an antennal segment. Abdominal segment 1 with pair of small, forked, unfringed gills.
![](https://static.macroinvertebrates.org/gigapans/198003/images.25b802990e2c2dcdf8ea29eb3fd41e2f/198003-617x240.jpg)
Dorsal