Golden Stone
Calineuria californica
Key Identification Characters - nymph: 2
- Two tails at least as long as abdomen.
- Thick filamentous gill tufts at base of each leg.
- Body light brown with dark markings on abdomen and thorax.
- Body length of mature nymphs (excluding tails) 20-30mm.
Similar nymphs: 2
Two species make up the stoneflies commonly called golden stones. H. pacifica can be quickly distinguished from C. californica by the pair of gill tufts between its tails and its darker color. The other stonefly that could be confused with golden stones is Skwala americana (Brown Willow Fly), but Skwala lacks gills at the base of its legs.
Key Identification Characters - Adult 2
- Two tails nearly as long as abdomen.
- Wings light tan in color.
- Body color a rich golden brown.
- Remnants of gills present at base of legs.
- Body length (excluding tails) 20-30mm. Males noticeably smaller than females (see above).
Also check nymphal shucks for gill remnants between tails. H. pacifica may have them. C. californica will not.
Similar adults: 2
Adult golden stones can be quickly identified by their size and color and by the gill remnants at the base of each leg (a small hand lens will be needed to see them). Separating the two species of golden stones as adults is much harder than for the nymphs. One of the easiest ways is to look at the nymphal shuck from a recently emerged adult. The presence or absence of gill remnants between the tails can provide the answer. Alternatively adult genitalia can be checked to confirm species.
Habitat & Distribution 2
Unlike salmonflies, golden stones are widely distributed and abundant throughout the West. Good numbers can be found in a wide range of stream types from small mountain streams to large valley rivers, wherever rocky riffles and runs occur. H. pacifica has been called the most widely distributed stonefly species in the Rocky Mountains (Baumann R. W., et.al. 1977.The Stoneflies (Plecoptera) of the Rocky Mountains. Memoirs of the American Entomological Society, Number 31. ).
In Oregon both species of golden stones are common and often abundant on both sides of the Cascades. West of the Cascade mountains C. californica tends to be more common, while east of the Cascade mountains H. pacific dominates. It is not uncommon however, to find both species in the same stream on either side of the Cascades.
Life Cycle - Emergence: 2
Golden stones, like the salmonfly, have a multi-year life cycle, with nymphs taking two to three years to complete development. Once mature, nymphs crawl along the stream bottom to areas near shore. Emergence occurs at night with nymphs crawling from the water. Where salmonflies and golden stones coexist, salmonflies generally emerge shortly before golden stones, but after a week or so, adults of both species will be present.
Oregon Emergence Period: mid May to late August.
Metolius: Abundant. Emerge July-August?
McKenzie: Moderate numbers. Emerge May-June?
Necanicum/Nehalem: Moderate numbers. Emerge May-June?
Sources and Credits
- (c) Jerry Schoen, all rights reserved, uploaded by Jerry Schoen
- (c) Jerry Schoen, some rights reserved (CC BY-SA)
