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Montana Field Guide

Montana Field Guides

Least Roachfly - Yoraperla brevis

Native Species

Global Rank: G5
State Rank: SNR

Agency Status

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General Description
This is the most common genus of the family Peltoperlidae in the Rocky Mountains. Yoraperla species are found in headwater flowing water habitats in the northern Rocky Mountains and Y. brevis is the most common species in the whole group
The genus is distinguished by the presence of two pairs of cervical gills, one on the inside and one on the outside of the lateral cervical sclerites
Yoraperla species are abundant in accumulations of leaf material and probably act as shredders of allochthonous material in heterotrophic lotic ecosystems.

Range Comments
Rangewide, Yoraperla brevis is a common Rocky Mountain small stream inhabitant known to occur in Idaho and Montana (NatureServe 2006) and probably other Pacific NW states such as northern Washington and BC, but distribution data for U.S. states and Canadian provinces is incomplete or has not been reviewed for this taxon.

In Montana Mineral County in western Montana (Stagliano, this study).

Observations in Montana Natural Heritage Program Database
Number of Observations: 171

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

This species occurs in small high-gradient creeks and streams near their headwater sources (Baumann et al. 1977). Nymphs were found in large woody debris and mossy cobbles. Merritt and Cummins (1996) describe Yoraperla trophic relationships as shredders (large organic detritus, plant materials).

Food Habits
Merritt and Cummins (1996) report that members of the family, Peltoperlidae are trophically shredder-detritivores; eating large particulate organic materials such as detritus, leaves and plant materials.

Threats or Limiting Factors
Specific threats to Yoraperla have not been identified. In general, stonefly populations are affected by changes to aquatic habitat, such as alteration of flow patterns, streambed substrate, thermal characteristics, and water quality. Alteration and degradation of riparian / aquatic habitat is the primary concern for Northern Region 1 Forest Service populations.

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Citation for data on this website:
Least Roachfly — Yoraperla brevis.  Montana Field Guide.  .  Retrieved on , from