Drunella

Needham, 1905

Blue-winged Olives, Spiny Crawler Mayflies

Species Guides

11

Drunella is a of spiny crawler mayflies in the Ephemerellidae, comprising at least 20 described . These mayflies are aquatic insects with nymphs that inhabit stream environments and are significant components of freshwater . are important to fly fishermen, who commonly refer to them as "Blue-winged Olives" and imitate them with artificial flies. Some species, such as Drunella grandis (the green drake), are particularly valued as trout food sources.

Drunella coloradensis by (c) Trevor Van Loon, some rights reserved (CC BY), uploaded by Trevor Van Loon. Used under a CC-BY license.Spiny crawler mayfly, Drunella coloradensis (9638216411) by Bob Henricks from Charlottesville, United States. Used under a CC BY-SA 2.0 license.Spiny crawler mayfly, Drunella coloradensis (9641453786) by Bob Henricks from Charlottesville, United States. Used under a CC BY-SA 2.0 license.

Pronunciation

How to pronounce Drunella: //druˈnɛl.lə//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

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Habitat

Stream environments, including mountain streams and flowing water systems. Nymphs occupy benthic and show microdistribution patterns related to fine substrate characteristics. Some exhibit flexibility along altitude gradients.

Distribution

North America (including Vermont, Wyoming), China (Shennongjia National Park), and Japan. The has a Holarctic distribution pattern with documented across temperate regions.

Life Cycle

Hemimetabolous development with aquatic nymph stage and terrestrial winged stage. Nymphs are the primary feeding and growth phase. Specific show flexibility along environmental gradients; for example, Drunella submontana exhibits adaptive shifts in life history traits across altitude gradients in China. Drunella coloradensis nymphs have been observed to drift primarily during dark periods, indicating or activity patterns.

Behavior

Nymphs exhibit behavioral sensitivity to environmental stressors. Drunella coloradensis nymphs show increased drift in response to pH reductions, with drift activity concentrated during dark periods and rapid response within 2-4 hours of pH change. At intermediate pH decline (pH 7.01), nymphs reduce sitting behavior and increase burrowing; at greater acidity (pH 6.02), burrowing returns to control levels while drifting and crawling increase. Ventilatory behaviors increase with pH decline regardless of severity.

Ecological Role

Important prey item for salmonid fishes including trout. Nymphs contribute to benthic dynamics and serve as bioindicators of stream health, with behavioral responses offering sensitive indicators of sub-acute stress in aquatic communities. Increased drift under stress may alter -prey encounter rates and community-level processes.

Human Relevance

Highly significant to recreational fly fishing. are imitated with artificial dry flies, while nymph patterns copy the aquatic stage. Drunella grandis (green drake) and related are among the most important hatches for trout anglers in North America. Fly patterns include extended-body designs to match the slender of adults. Knowledge of Drunella , timing, and preferences is considered essential for successful angling.

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