The Carlisle Mosquito Online

Friday, March 6, 2009


Handsome Fungus Beetle

Two of my favorite kinds of organism (beetles and fungi) are not in abundance in the winter

(Photo by Kay Fairweather)

months, so I take extra pleasure from those I find. On Saturday, February 28, I was bringing firewood into the house and discovered that one of the pieces was serving as a hibernaculum for a beetle. I first thought the beetle was some type of ladybug but it turned out to be a Handsome Fungus Beetle. It was definitely a looker but the name is not the result of my editorializing. There is a family of beetles, the Endomychidae, where all 45 species are known as Handsome Fungus Beetles. None of my books give common names for individual species. This one, Endomychus biguttatus, according to the Kaufmann Guide, is found in eastern U.S. forests and is the only one likely to be noticed by the casual observer, but even so it is not common.

Distinguishing characteristics: These beetles are about a quarter-inch long. They have black heads and orange wing covers (elytra). Each wing cover has two black spots, one small and one large. You can distinguish them from ladybugs (which are really beetles, not bugs) because the antennae are longer than those of the ladybugs and more prominently clubbed at the end. Also, there are a couple of grooves or dimples on the thorax, and the front edge of the thorax is indented.

Spotted, dotted and besotted: The species name, biguttatus, is from the Latin meaning two-spotted, which refers to the black spots on the wing covers. If I were to give this beetle a common name I might call it the bi-spotted, double-dotted, twin-blotted Handsome Fungus Beetle. It was not so handsome that I was besotted, but I did return the firewood to a separate stack which won’t be burned this year and the beetle will have a chance to complete its natural lifecycle.

Beetle lifecycle: Beetles typically have one generation per year (some have more), and most spend the winter in their larval or pupal stages. This one though, like those Asian ladybugs that come indoors in the early winter, finds a protected spot to hunker down in its adult form for the winter. It will mate and lay eggs on or near fungi in the summer. The larvae feed on fungi, pupate, and emerge as adult beetles some time before winter.

Other fungus beetles: There are around 300,000 species of beetles in the world so it shouldn’t be too surprising to find that there are several groups or families whose life cycle is dependent in some way on fungi and are so-named. In addition to Handsome Fungus Beetles, we have Hairy Fungus Beetles and Silken Fungus Beetles; there are Minute Fungus Beetles which are about one millimeter long; there is the comparatively large Horned Fungus Beetle which I often find in Carlisle; and of course we have the family Erotylidae, who take their name from the Greek erotilos, meaning sweetheart or darling. They are not known as Erotic Fungus Beetles but as less salacious Pleasing Fungus Beetles – which are never hairy while Hairy Fungus Beetles can be pleasing. Fungi too can be handsome, hairy, minute, pleasing etc., but the adjective in the beetle names qualifies the beetle not the fungus.

Sources: Kaufman Field Guide to Insects of North America, Eric A. Eaton and Kenn Kaufman; Petersen Field Guide to Beetles, Richard E. White; Insects: Their Natural History and Diversity, Stephen A. Marshall.

© 2009 The Carlisle Mosquito