Yellow grubs: Common parasite found in Idaho panfish

After catching a small pile of bluegill at a favorite local fishing spot, the time comes for fileting. But while cutting into the fish to make a mouth-watering pile of fish tacos, a grub-looking worm starts wriggling around in the meat. Some questions naturally come to mind like: what is that? Is it cause to throw the fish out? What will that do to lunch plans?

Many anglers have encountered the common panfish parasite called “yellow grub,” and although it looks like something from an episode of "Fear Factor," the Idaho Department of Fish and Game advises against eating them raw. Cooking is preferred!

Panfish with yellow grub disease are infected with tiny yellow or white “grubs” that live in the meat. Yellow grubs host in panfish because they ultimately need to get inside a fish-eating bird, like herons, to reproduce. Yellow grubs live out their youth in snails, which get eaten by panfish, which then get eaten by birds.

Because their target host is a bird, grubs don’t pose much threat to humans, but Fish and Game still doesn’t recommend eating the grubs, even if a fishing buddy double dog dares it. When eaten raw, yellow grubs can attach to the throat, causing irritation and a sore throat.

If grubs turn up while cleaning a fish, there's no need to throw it out, just make sure to cook the fish thoroughly.

Yellow grubs are most prevalent in the spring, with a small resurgence in fall. Despite many panfish carrying the parasites, research suggests grubs have little to no impact on panfish populations.

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Jennifer Bruns is a regional communications manager with the Idaho Department of Fish and Game.