Springs Stripetail - Isoperla petersoni
State Rank Reason (see State Rank above)
The Springs Stripetail is currently ranked a "S2" Species of Concern in MT at risk because of very limited and/or potentially declining population numbers, range and/or habitat, making it vulnerable to extirpation in the state. Limited sites with small populations, but also difficult to identify without adult specimens.
- Details on Status Ranking and Review
ScoreU - Unknown
ScoreU - Unknown
Area of Occupancy
CommentLB = 4-40 km (about 2.5-25 miles)
Length of Occupancy
ScoreLB - 4-40 km (about 2.5-25 miles)
ScoreE - Relatively Stable (±25% change)
ScoreE - Stable. Population, range, area occupied, and/or number or condition of occurrences unchanged or remaining within ±10% fluctuation
ScoreF - Widespread, low-severity threat. Threat is of low severity but affects (or would affect) most or a significant portion of the population or area.
SeverityLow - Low but nontrivial reduction of species population or reversible degradation or reduction of habitat in area affected, with recovery expected in 10-50 years.
ScopeModerate - 20-60% of total population or area affected
ImmediacyLow - Threat is likely to be operational within 5-20 years.
ScoreB - Moderately Vulnerable. Species exhibits moderate age of maturity, frequency of reproduction, and/or fecundity such that populations generally tend to recover from decreases in abundance over a period of several years (on the order of 5-20 years or 2-5 generations); or species has moderate dispersal capability such that extirpated populations generally become reestablished through natural recolonization (unaided by humans).
ScoreA - Very Narrow. Specialist. Specific habitat(s), substrate(s), food type(s), hosts, breeding/nonbreeding microhabitats, or other abiotic and/or biotic factor(s) are used or required by the Element in the area of interest, with these habitat(s) and/or other requirements furthermore being scarce within the generalized range of the species within the area of interest, and, the population (or the number of breeding attempts) expected to decline significantly if any of these key requirements become unavailable.
This rare, nicely patterned, cold-water Isoperla stonefly is limited in distribution in Montana. It is found elsewhere in the Northern and Southern Rocky Mountains including Alberta, British Columbia, Wyoming, Idaho, and Utah.
Limited in distribution in Montana, but is found elsewhere in the Northern and Southern Rocky Mountains including Alberta, British Columbia, Wyoming, Idaho, and Utah. This species is known from two collection sites in Montana, widely dispersed in Glacier and in a single stream in Gallatin County.
Observations in Montana Natural Heritage Program Database
Number of Observations:
(Click on the following maps and charts to see full sized version)
Map Help and Descriptions
(Observations spanning multiple months or years are excluded from time charts)
This species occurs in small springs and spring-fed creeks (Baumann et al. 1977). Nymphs were found in large woody debris and mossy cobbles. Merritt and Cummins (1996) describe Isoperla trophic relationships as predators (especially chironomids, and blackflies).
Merritt and Cummins (1996) report that members of the families, Perlidae and Perlodidae, are largely predators eating other aquatic invertebrates, especially Diptera (Chironomidae and Simuliidae, midges and blackflies) and mayflies.
Adults emerge from late May-October.
Limited in distribution in Montana, but is found elsewhere in the Northern and Southern Rocky Mountains including Alberta British Columbia, Wyoming, Idaho, and Utah. This species is known from two collection sites in Montana; widely desperate in Glacier and in Gallatin Counties.
Threats or Limiting Factors
Specific threats to MT populations of Isoperla have not been identified. In general, stonefly populations are affected by alterations of aquatic habitat such as changes of flow patterns, streambed substrate, thermal characteristics, and water quality. Degradation and warming of aquatic habitat is the primary concern for any population.
- Literature Cited AboveLegend: View Online Publication
- Baumann, R.W, A.R. Gaufin, and R.F. Surdick. 1977. The stoneflies (Plecoptera) of the Rocky Mountains. American Entomological Society, Philadelphia.
- Merritt, R.W. and K.W. Cummins. 1996. An introduction to the aquatic insects of North America. 3rd Edition. Kendall/Hunt Publishing Company. Dubuque, Iowa. 862 pp.
- Additional Sources of Information Related to "Insects"