Ischnura verticalis

(Say, 1840)

Eastern Forktail

Ischnura verticalis, the Eastern Forktail, is a small in the Coenagrionidae. Larvae exhibit behavioral through depth selection in water columns, moving deeper at higher temperatures and shallower when cooler. Development is temperature- and prey-dependent, with faster development at higher temperatures and food availability. Males typically develop faster than females, with sexual differences in larval and instar progression. emerge over extended periods, with in temperate .

Ischnura verticalis by (c) Patrick Hanly, some rights reserved (CC BY), uploaded by Patrick Hanly. Used under a CC-BY license.

Ischnura verticalis by the Smithsonian. Used under a CC0 license.

Pronunciation

How to pronounce Ischnura verticalis: /ˈisknʊrə vɜːrtɪˈkaːlɪs/

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Habitat

Aquatic freshwater environments including ponds, lakes, and slow-moving waters with emergent vegetation. Larvae occupy variable depths depending on thermal and food conditions, with depth selection documented in response to temperature gradients and food availability.

Distribution

North America; recorded from southern Ontario through the northeastern and midwestern United States. Western range extends to Colorado, with documented in Vermont and other eastern states.

Seasonality

on the wing primarily during warmer months; period can extend over 97 days in temperate . with extended adult emergence period.

Diet

Larvae are predatory, feeding on small aquatic . Laboratory studies indicate Daphnia is commonly used prey in captive settings, though natural diet in wild is not explicitly documented in available sources.

Life Cycle

with extended period lasting at least 97 days in some . Larval development includes multiple instars with ontogenetic behavioral changes; larger instars show increased feeding frequency, activity, and distinct behavioral patterns compared to smaller instars. Final instar males develop faster than final instar females. Emergence sex ratio approximately 1:1.

Behavior

Larvae exhibit depth selection : at higher temperatures and abundant food, larvae select deeper waters; at lower temperatures or scarce food, they remain closer to the surface. This represents behavioral balancing growth optimization against risk. Ontogenetic behavioral changes occur through instars, with larger larvae showing increased feeding activity and distinct behavioral repertoires including wave, straight abdomen raise, and rotate + out behaviors. Male larvae in antepenultimate instar are more active and mobile than females. Larvae reduce feeding activity in response to fish , with behavioral response and cost of reduced feeding varying by size.

Ecological Role

in aquatic as larvae; serves as for eugregarine protozoan . Contributes to nutrient cycling and energy transfer between aquatic and terrestrial through .