Giant Needlefly - Megaleuctra stigmata
This is a small black stonefly in the family; Leuctridae. Like most of the species in the rolled-winged family, this species hatches early in the year often when snow is still on the ground, where they can be noticed quite easily crawling around along the banks of streams.
Adult morphology: Body length is 11-13 mm; length to tip of wings is 15 mm. Head, thorax, abdomen, and appendages are dark brown. The three ocelli form a nearly unilateral triangle. The pronotum is about as wide as long, margins are light colored, and a central area is darker and has an indication of a wide, longitudinal, lighter median stripe. No gill remnants are on any body area. For more detailed description see Frison (1942).
Nymph morphology: Body length is 15 mm. General color is light brown. Cercal segments are at least 17 mm. A continuous membranous fold is present along the sides of the first 7 abdominal segments. The tenth tergite is drawn out and contains a dorsal sclerotized structure. Subanal lobes are bulbous, not fused distally, and rather hidden between the tenth tergite and tenth sternite (Jewett 1954).
Rangewide, the species is known from Washington, British Columbia, Alberta, Idaho (Idaho & Latah County), Montana (Lake & Missoula County). It is known from <30 EO's (most in Canada), mostly springs, seeps and small rheocrenes (NatureServe 2006). No map is available.
Observations in Montana Natural Heritage Program Database
Number of Observations:
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(Observations spanning multiple months or years are excluded from time charts)
Very little information exists about the ecology of this species (Baumann, Gaufin, and Surdick 1977). Merritt and Cummins (1996) report that members of the genus Megaleuctra are found in small springs and seeps, and are trophically shredder-detritivores.
Merritt and Cummins (1996) report that members of this family are trophically shredder-detritivores; eating large particulate organic materials such as detritus, leaves and plants.
No information is available.
Baumann, Gaufin, and Surdick (1977) describe this as a “rare species and it is reported to occur in only 2 counties in Montana.
Threats or Limiting Factors
Specific threats to MT populations of Megaleuctra stigmata 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 aquatic habitat is the primary concern for MT populations.
- 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.
- Cummins, K.W. and R.W. Merritt. 1996. Ecology and distribution of aquatic insects. Chapter 6, pages 74-86 in R.W. Merritt and K.W. Cummins (eds.) An Introduction to the Aquatic Insects of North America. Third Edition. Kendall/Hunt Publishing Company, Dubuque, Iowa. 862 pp.
- Frison, T. H. 1942. Descriptions, records and systematic notes concerning western North American stoneflies (Plecoptera). Pan-Pacific Entomologist 18(1): 9-16.
- Jewett, S.G., Jr. 1954. New stoneflies (Plecoptera) from western North America. Journal of the Fisheries Research Board of Canada 11: 543-549.
- NatureServe. 2006. NatureServe Explorer: An on-line encyclopedia of life [web application]. Version 4.7. Arlington, Virginia.
- Additional Sources of Information Related to "Insects"