Montana Field Guide

This is a large vividly-marked, black and yellow dragonfly with long abdomen, the eyes are smallish and barely touching. They are strong flyers and when perched often hang at a 45° angle. The female has a spikelike ovipositor. This species inhabits lotic systems in western Montana (small woodland streams and rivers). There is only 1 genus and 1 species of this family of dragonflies in NorthWestern North America.

Only drangonfly in western Montana with black abdomen and yellow spots.

The habitat of the Pacific Spiketail is clear, shady foothill and mountains streams with either sand or mud substrate and steady current. Away from water this species tends to forage along forest openings and clearings or brushy ravines. Pacific Spiketails often perch on trees and small branches of shrubs for lengthy periods of time (Dunkle 2000, Paulson 2009).

Larvae feed on a wide variety of aquatic insects, such as mosquito larvae, other aquatic fly larvae, mayfly larvae, and freshwater shrimp.
Adult- This damselfly will eat almost any soft-bodied flying insect including mosquitoes, flies, small moths, mayflies, and flying ants or termites.

Male Pacific Spiketails patrol very long stretches of streams in low, steady flights usually turning around when encountering an obstacle or open pond. They will often return to same perch repeatedly. Females usually avoid breeding sites until time for egg laying as patrolling males will harass them. Oviposition is completed in shallow water along stream edges driving eggs into the substrate with vertical thrusts (Dunkle 2000, Paulson 2009).

Intact forested riparian areas are essential for this species along it's river corridor

Threats to this species would be clearcutting riparian forests along the corridors of the streams they inhabit.