Searching for Silver Sedge

(Photo: Odontocerum albicorne, Trawscoed, North Wales, August 2015. Photo by Janet Graham, via Wikimedia Commons. Licensed under CC BY 2.0.)

Two days ago I spent almost four hours on the phone with my friend Dave Skok. We talked about trout and striped bass fishing, sight casting, dry flies, spring creeks, hatches, and fly rods. That conversation somehow sent me looking for a particular insect I thought I might have seen on my trout water, the Moesian karst stream Crnica in eastern Serbia.

I have spent countless hours reading its currents, turning over its river stones, and trying to fool its trout. Yet even after all these years, the river still manages to keep secrets from me. It concerns a magnificent, heavily structured caddisfly that I suspect may be hiding right under our noses: Odontocerum albicorne, famously known to fly anglers as the Silver Sedge.

If you look at European entomology maps, the Silver Sedge is a documented resident of the region. It has been recently documented in Montenegro and is present in Bulgaria. It is also included in published lists of the Trichoptera fauna of Serbia. However, I have a confession to make: I don't believe I have ever personally seen one on the Crnica.

But before you call me crazy for speculating on its existence, consider the timeline. Odontocerum albicorne is a summer specialist. Its peak emergence occurs from June through July and stretches into August. For many years, my calendar has kept me away from the river during those exact sweltering summer months.

Could this beautiful insect be hatching in the warm summer twilights while I am wading the flats around Boston, looking for striped bass, far away from the Crnica? I think it is entirely possible.

I have, over the years, observed an enormous biodiversity of aquatic insects on the Crnica. I have also found that another almost identical species is documented in the Balkans, Odontocerum hellenicum. Based on the current data, it seems that O. hellenicum would be more likely to occur farther south, in the Stara Planina region.

To understand why the Crnica is a prime candidate for the Silver Sedge, you have to look at how these insects live. The larvae are master underwater stonemasons, constructing incredibly strong, curved defensive cases entirely out of tightly bound grains of sand. They don't just live anywhere—they require clean, permanent, moderate-to-fast flowing water with a rich substrate of gravel and boulders.

The pristine, well-oxygenated upper stretches of the Crnica fit this ecological profile perfectly.

When they do emerge, they are not small caddisflies. The adults boast a substantial forewing length of 13–18 mm, easily identified by their distinctively long, aggressively toothed antennae and striking silver-grey appearance when resting on riparian foliage. For a trout, an adult Silver Sedge or its swimming pupa represents a high-calorie steak dinner.

I am hoping that next June I will dedicate some time to setting UV light traps and doing more sampling of insects along the banks of the Crnica. I hope this ghost story will eventually be solved!

A Few Things I Found Down the Rabbit Hole

While I was a biology student in Belgrade in the late 1980s, one of my dearest professors was Miloje Brajković. I told him way back then about my interest in fly fishing and angling entomology. He smiled and gave me some tips and encouragement as I began collecting specimens, along with resources for identification.

So I am listing his work on top…

Živić, I., Marković, Z. & Brajković, M. (2006). Contribution to the faunistical list of Trichoptera (Insecta) of Serbia.Acta Entomologica Slovenica 14(1): 55–68.
— A very useful general Serbian caddisfly reference; the revised list increased the known Serbian Trichoptera fauna from 173 to 186 species.

Novaković, B., Stojanović, K., Marković, V., Radojević, A., Božanić, M. & Živić, I. (2017). A Valorization of Benthic Invertebrate Fauna of the Mlava River (Eastern Serbia).
— The Mlava survey: 197 benthic taxa recorded during 2009–2014.

Stojanović et al. (2018). Odontocerum hellenicum (Malicky, 1972) (Trichoptera: Odontoceridae) as a host of Agriotypus armatus (Curtis, 1832) (Hymenoptera: Ichneumonidae) — the first finding for Serbia.
— Particularly relevant to the southeastern-Serbia angle.

Klima, F. & Hodges, J. C. (1987). Description of the Larva and Female of Odontocerum hellenicum Malicky, 1972, as Compared to O. albicorne Scopoli, 1763 (Trichoptera: Odontoceridae). Aquatic Insects 9(3): 177–183.
— The really useful hellenicum/albicorne comparison.

Kiss, O. & Pfliegler, W. P. (2011). The biology and life cycle of Odontocerum albicorne (Scopoli, 1763) (Trichoptera).
— Excellent general natural-history source; also discusses the Balkan Odontocerum species and the Bulgarian O. hellenicum records.

Kumanski, K. (1981). Faunistic investigations on Bulgarian Trichoptera to June, 1980 — with a revised check-list. In: Moretti, G. P. (ed.), Proceedings of the 3rd International Symposium on Trichoptera, Series Entomologica 20: 139–147.
— The older Bulgarian source behind the O. hellenicum connection.

Malicky, H. (1972). Weitere neue Arten und Fundorte von Westpaläarktischen Köcherfliegen (Trichoptera), von allem aus dem östlichen Mediterrangebiet. Mitteilungen der Entomologischen Gesellschaft Basel 22: 25–68.
— The original description of Odontocerum hellenicum.

Bozdoğan, H., Bilalli, A. & Ibrahimi, H. (2025). New caddisfly records (Insecta, Trichoptera) for Montenegro and Ecoregion 5, Dinaric Western Balkans: distributional and ecological insights. Biodiversity Data Journal 13: e146076.
— O. albicorne was documented on the Zeta River in Montenegro using a UV light trap on July 22, 2024; five males and nine females were recorded.