Insects & Flies

The aquatic entomology of the Eastern Cape Highlands by Ed Herbst.

The Aquatic Entomology of
the Highlands

The streams and rivers of the Eastern Cape Highlands are nutrient-rich environments that support an abundant and varied food chain. This abundance accounts for the trophy trout and yellowfish the region consistently produces. A thorough knowledge of the full range of aquatic insects is not essential — but understanding the dominant food forms will improve your results considerably.

Mayflies (Baetidae)

All four major mayfly types — clingers, crawlers, swimmers, and burrowers — are found in abundance. The most prolific species are from the Baetis family, particularly Baetis harrisoni and Demoreptus natatensis. The tiny Tricorythidae discolor (the “Angler’s Curse”) hatches in clouds over dams and the slower, silt-bottomed sections.

 

Mayfly nymphs are the dominant food source for trout in these rivers. A nymph fished dead-drift behind a yarn strike indicator is the most consistently productive technique in the Highlands.

Caddisflies (Trichoptera)

Caddisflies are an important food source in larval, pupal, and adult form. The most commonly found species in the Highlands is Cheumatopsyche afia, which is highly variable in colour. Adults tend to skitter across the water surface after hatching – a twitched dry fly often works well under these conditions. Hatches often occur at twilight. A #16 CDC and Elk covers most bases.

Black Flies (Simulium) – Lord of the Rapids

Research consistently shows that black fly larvae are among the most important food sources for trout in mountain streams. Stomach content analysis of Bell River trout has confirmed this locally: one sample contained 17 Baetis nymphs and 9 Simulium larvae – and nothing else.


Matching Simulium larvae was difficult until UV-light-cured resins derived from dentistry became available. Ed Herbst’s articles on the subject are available on Tom Sutcliffe’s Spirit of Fly Fishing website.

Beetles

The most common beetle in the Highlands is the bronze-green leaf-eating Chrysomelid beetle, found in abundance from October through November and again in late summer and autumn. This species lives on the leaves of invasive Weeping Willows, which are prolific in Rhodes. Trout rarely refuse a beetle pattern, and will often take one even during a heavy mayfly or caddis hatch. Ed Herbst’s Bushwhack Beetle is a proven local pattern.

Ants

Ants form a critical part of the trout’s mid-summer diet. Research by Jeff Morgan found that in a month-long study, ants appeared six times more frequently in stomach samples than hoppers. A sunken ant pattern is more visible to the fish than a floating one.

Most productive fished in April and May, when hoppers reach maximum size before the first frosts. Fish a hopper after 10am when insects become active. Research suggests beetles and ants are generally more productive terrestrial imitations than hoppers.

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