Stoneflies
Plecoptera
Classification
- Phylum: Arthropoda
- Subphylum: Hexapoda
- Class: Insecta
- Order: Plecoptera
Pronunciation
How to pronounce Plecoptera: /plɛˈkɒptərə/
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Images
Summary
Plecoptera, commonly known as stoneflies, is an order of insects characterized by their long antennae, membranous wings, and aquatic nymphs. They thrive in clean, well-oxygenated waters and are an important ecological indicator of water quality.
Physical Characteristics
Plecoptera have simple mouthparts, long, multiple-segmented antennae, large compound eyes, and two or three ocelli. Their legs are robust and end in two claws, and they possess long, paired cerci projecting from the tip of their abdomens. The wings are membranous with complex venation and fold flat over their backs. Adults are generally not strong fliers; some species are entirely wingless.
Identification Tips
Plecoptera can be identified by their long antennae, multiple-segmented bodies, robust legs, and the presence of cerci. The hind wings are notably folded down the back when at rest, which differentiates them from other insects.
Habitat
Nymphs are primarily found in cool, clean, well-oxygenated streams, often under stones or along rocky shores of cold lakes. Adults may be found resting on stones logs in water, or on leaves and trunks of nearby trees and shrubs.
Distribution
Plecoptera is found worldwide, except for Antarctica. They are present in both the Southern and Northern Hemispheres, with distinct populations in those regions.
Diet
Nymphs feed on algae, diatoms, mosses, submerged leaves, and other aquatic invertebrates. Most adults do not feed, while some, particularly winter stoneflies, will consume blue-green algae and foliage.
Life Cycle
Females lay several egg masses, potentially totaling over 1,000 eggs, which may hatch within 2 to 3 weeks. Nymphs remain in the nymphal stage for one to four years, completing 12 to 36 molts before emerging as adults. The adult lifespan is generally only a few weeks.
Reproduction
The female stoneflies can fly over water to deposit eggs, which are covered in sticky coatings to adhere to surfaces. Some species undergo a diapause, delaying hatching until conditions are favorable.
Ecosystem Role
Plecoptera are indicators of good water quality due to their intolerance to pollution. Their presence in aquatic systems signifies healthy ecosystems, and they play a role in nutrient cycling as both herbivores and predators.
Collecting Methods
- Aquatic collection with nets
- Light trapping for adults near water bodies
Preservation Methods
- Ethanol preservation
- Pinning specimens
Evolution
Plecoptera is believed to be one of the most primitive groups of Neoptera, with fossil relatives dating back to the Carboniferous and Lower Permian geological periods. Their modern diversity is thought to originate from the Mesozoic.
Misconceptions
Some might confuse stoneflies with other aquatic insects; however, their unique wing structure and habit of living in clean water set them apart.
Tags
- Stoneflies
- Plecoptera
- Insects
- Benthic organisms
- Aquatic ecology