Small Winter Stoneflies
Capniidae
Classification
- Phylum: Arthropoda
- Subphylum: Hexapoda
- Class: Insecta
- Order: Plecoptera
- Superfamily: Nemouroidea
- Family: Capniidae
Pronunciation
How to pronounce Capniidae: //kæpˈnaɪ.ɪˌdiː//
These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.
Images
Summary
Capniidae, or small winter stoneflies, is a family of stoneflies characterized by their small size, dark coloration, and reduced wing venation. They dwell in the hyporheic zone of freshwaters and are noted for their cold tolerance and often endemic populations.
Physical Characteristics
Adults typically <10 mm (average ~7 mm); blackish or dark brown with reduced wing venation; forewings with few cross veins and elongate cells; cerci longer than greatest width of pronotum; nymphs slender, brown or blackish with no thoracic or abdominal gills.
Identification Tips
Look for adults walking on snow or resting on concrete bridges over streams. Nymphs can be identified by their slender bodies and the distinctive groove along the abdomen, and are often found beneath rocks in clean rivers and streams.
Habitat
Nymphs dwell in the hyporheic zone, while adults are found in cold, clean rivers and streams, often emerging when snow is present in winter and early spring.
Distribution
Widespread in North America and globally with nearly 300 species distributed throughout the Holarctic region; many species are endemic to small ranges due to their adaptations to cold environments.
Diet
Nymphs feed on aquatic plant material; adults feed on blue-green algae.
Life Cycle
Adults emerge from November to June; nymphs are present in aquatic environments and only move out of their substrate before moulting into adults.
Ecosystem Role
Play a role in freshwater ecosystems as both herbivores (nymphs) and a food source for predators.
Collecting Methods
- Using nets to sample nymphs from stream beds
- Sampling with light traps for adults
Preservation Methods
- Ethanol preservation
- Pinning for adults
Evolution
Evolution of tolerance for cold temperatures has isolated some populations in specific mountain valleys, resulting in endemism.
Similar Taxa
Misconceptions
Some species are thought to be monophyletic despite evidence suggesting polyphyly, particularly in the genus Capnia.
Tags
- plecoptera
- capniidae
- stoneflies
- winter
- nymphs
- adults
- aquatic insects