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Archive for July 1, 2022

Hemlock Varnish Shelf & Pleasing Fungus Beetles

Two beauties in one place – Hemlock Varnish Shelf (Ganoderma tsugae), an aptly-named polypore fungus that is found growing on Eastern Hemlocks, and Pleasing Fungus Beetles (Megalodacne heros) devouring Hemlock Varnish Shelf in large numbers.

The dry, shiny upper surface of the growing Hemlock Varnish Shelf caps is brightly colored, often in flaming shades of red or orange.  Similarly, the beetles are bright orange and black, appearing to match the color of their host fungus. The combination is eye-catching, to say the least.

Although these beetles are not rare, they are seldom noticed perhaps because the adults are nocturnal. They sometimes congregate under bark or rotting wood usually within 25 feet of Hemlock Varnish Shelf-infested trees and stumps. They emerge at dusk to feed throughout the night. Females lay their eggs on the fruiting bodies of shelf fungi in the genus Ganoderma and other wood-rotting fungi. Pleasing Fungus Beetle larvae hatch and feed in the woody fruiting structures of shelf fungi, as do adults.

A wide variety of fungi serves as hosts for the family as a whole, but each Pleasing Fungus Beetle species seems to be specific to a certain group of fungi. In this case the beetle Megalodacne heros is associated with Hemlock Varnish Shelf.

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