order
Coleoptera
“Adult Beetles”
Coleoptera
“Larval Beetles”
Diptera
“True Flies”
Ephemeroptera
“Mayflies”
Hemiptera
“True Bugs”
Lepidoptera
“Aquatic Caterpillars, Snout Moths”
Megaloptera
“Alderflies, Dobsonflies, and Fishflies”
Odonata
“Dragonflies and Damselflies”
Plecoptera
“Stoneflies”
Trichoptera
“Caddisflies”
family
Elmidae
Ancyronyx variegatus
“Riffle Beetles”
Genus Overview
This genus is represented as one species in North America. There are several species known across the globe as "Spider Riffle Beetles" because of their long legs. They are univoltine with six instars.
Characteristics
POLLUTION TOLERANCE
Southeast: 6.9 and higher
Upper Midwest: 6 and higher
Midwest: 4 and higher
FEEDING HABITS
Collector / Gatherer
Scraper / Grazer
Scraper / Grazer
MOVEMENT
Clinger
Sprawler
Sprawler
DISTRIBUTION
Widespread (east of the Rocky Mtns.)
HABITAT
Lotic-depositional
Lotic-erosional
Lotic-erosional
Diagnostic Characters
Order
Elytra
Family
5-Segmented Tarsi
Big Claws
Last Tarsal Segment
Thread-like Antennae
Genus
Antennae With 11 Segments
Basal Tooth On Claw
Prosternal Process
Tomentum of tibia
+ Expanded Character List
Order:
Adults with hardened forewings (elytra) covering the hind wings.
Family:
Terminal segment of each antenna no longer than combined length of 2 preceding segments; antennae thread-like. Elytra concealing entire abdomen or exposing only part of 1 tergite. Each leg with 5 tarsal segments, last tarsal segment about as long as other segments combined and with big claws. Abdomen with 5 visible segments.
Genus:
Hind coxae similar to other coxae. Posterior margin of prosternal process about as wide as head. Legs elongated. Antennae 11 segmented. Elytra without sublateral carinae. Pronotum with transverse impression.
Dorsal
Ventral