Fly Fish Food Shop Talk Podcast · Fly Fish Food

Shop Talk Podcast Ep 35 | Roger Gold - Metamorphosis

·48 min·4 clips

Roger Gold reveals why fish stop feeding during molting—their stomach lining is ripped out.

This episode features Roger Gold, an entomologist and professor, returning to the Fly Fish Food Shop Talk Podcast by popular demand. Hosts engage Roger in a detailed conversation about insect biology and its direct application to fly fishing. The discussion centers on the process of metamorphosis and how an insect's life cycle dictates fish behavior. Roger explains that during molting, an insect sheds the exoskeleton lining its stomach, making feeding impossible for several days. He describes how temperature critically regulates insect development, with cold slowing metabolism and warm water reducing dissolved oxygen. Roger states insects comprise 80% of all animal species on Earth and can adapt quickly due to short generation times, like a housefly's 7-10 day cycle. He introduces the concept of a "cohort," where all offspring from a single egg-laying event develop in sync. The conversation covers sampling techniques, noting that high river flows can push insect populations downstream. Roger warns that high summer water temperatures stress fish by lowering oxygen and increasing lactic acid buildup. He details the "San Juan Shuffle," a banned practice of disturbing the riverbed that disrupts aquatic insect habitats. Roger outlines different metamorphosis types, from simple molts in scuds to complete metamorphosis with a pupal stage in caddisflies. He explains that the vulnerable emergence phase, when insects travel to the surface, is a prime feeding opportunity for fish. A surprising claim is that fish may not feed because their stomach lining is sore from shedding, similar to molting insects. Roger notes that insect populations in a disturbed riverbed can recover within a few months if conditions are favorable. He reveals that taxonomists have sometimes misclassified immature and adult stages of the same insect due to their drastically different forms. The idea that fish are "binge feeders" who disturb the riverbottom to flush out insects is presented as a key nymphing insight. Roger emphasizes that fly selection matters less than presenting a fly in the right place at the right time within the water column. A memorable moment is his humorous advice to always blame birds for how non-flying crustaceans like scuds reach upstream areas. The tone is conversational, educational, and often humorous, with hosts and guest sharing personal anecdotes. The style is a free-flowing interview that blends deep scientific concepts with practical fishing tips. This episode is ideal for fly fishers seeking a deeper understanding of aquatic entomology to improve their tactics. Listeners who prefer strictly narrative fishing stories or quick gear tips might find the detailed biological discussion less engaging.

As heard by us

Bug science, river sense, and shop talk that actually teaches something.

Roger Gold, an entomologist and professor, turns a loose chat into a bug lesson that earns its detours. The conversation moves between teasing and useful detail, with real entomology sitting alongside matching the hatch, high flows, and the question of why insects end up where…

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Want a real entomologist to explain what the bugs are doing on your river?

Read the full recommendation in PlayNext →

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