The lobster mushroom is really two fungi in one. It starts as an ordinary white mushroom, usually a Russula or Lactarius, and then a parasitic fungus, Hypomyces lactifluorum, attacks it. The parasite spreads a hard, bright orange skin over every surface, dotted with tiny pimples, and slowly bends the host into lumpy, twisted shapes. The host’s gills shrink to low, blunt ridges.
The takeover goes deeper than the surface. A 2018 study found that the host’s own DNA disappears step by step, starting at the rim of the cap, moving through the cap and ending in the stem, until very little of the original mushroom is left, even though the white flesh inside looks unchanged. With a hand lens you can see tiny reddish, flask-shaped structures on a mature specimen, where the parasite makes its spores. As it ages, the orange darkens toward purplish red.
In the Pacific Northwest its favorite host is a large white mushroom called Russula brevipes. Lobster mushrooms show up in summer and fall, wherever their hosts grow, and their color makes them easy to spot on the forest floor.
How to identify it
Looks like a firm, misshapen mushroom covered in a hard, bright orange to reddish orange crust with fine pimples. The gills are reduced to blunt ridges, and the flesh inside stays white and brittle. Older specimens darken to purplish red.
Look-alikes
A related parasite, Hypomyces luteovirens, also attacks Russula and Lactarius mushrooms, but it forms an olive yellow to dark green mold over the gills instead of an orange shell.
Habitat
Forest floor wherever its hosts grow, mainly white Russula and Lactarius mushrooms. In the Pacific Northwest it most often attacks Russula brevipes, and it fruits in summer and fall.
Photos
Sightings in the forest
103 research-grade sightings in Mt. Hood National Forest on iNaturalist, most recently on October 11, 2026. See them on iNaturalist →