The Oddest Beetle on Campus

Meet Thylodrias. Kind of sounds like a character from the Game of Thrones. But alas, it’s just an odd beetle about the size of the letter “d” in size ten print.

The Odd Beetle (Thylodrias contractus); Photo credit PJ Liesch
Adult male odd beetle (Thylodrias contractus); Photo credit PJ Liesch

Although, technically speaking, this one’s not just an odd beetle. It’s more like the king of odd beetles, so much so, that it’s actually known as the odd beetle. Kind of weird for a species belonging to a very common family: dermestidae. Other relatives in the dermestid bloodline include the common hide, larder, and carpet beetles, which occasionally find their way into that old, half-empty box of spaghetti noodles at the back of the kitchen cupboard. However, if you made a closer examination of the dermestid family tree, you’d find that the odd beetle sits alone: a solitary species in its own genus.

By now, you may be wondering: what really makes this one so odd? For starters, it’s a bit infatuated with humans and we only know of the species from human habitations. We even know of specimens from archaeological sites in Iran, but these days it’s most commonly found in museums. It’s somewhat ironic that such an interesting and unusual insect has a history of lurking around the home of the UW-Madison entomology department: Russell Labs1. Like many other museum pests, the odd beetle wanders around looking for a protein-rich meal to feed on.   It turns out that Russell Labs is home to plenty of potential food: millions of preserved insect specimens in the Wisconsin Insect Research Collection as well as preserved mammal and bird specimens in the Forestry and Wildlife Ecology wing of the building.

In addition to popping up in weird places, Thylodrias contractus also looks downright bizarre. With the naked eye, an adult female looks more like a bed bug or a small silverfish than a beetle. Technically, the females lack wings and have a larva-like appearance, which is strange in and of itself. Even the males of this species have a peculiar appearance and bear the meekest resemblance to other members of the family. Then there’s the quirky life cycle: developing larvae can go over a year without food. If times are really hard, they can borrow a page from The Curious Case of Benjamin Button and undergo retrogressive molting. With that elasticity in its development, the complete life cycle can vary from several months to several years.

All in all, rather peculiar.

1 Mertins, J. W. 1981. Life History and Morphology of the Odd Beetle, Thylodrias constractus. Ann. Ent. Soc. Am. 74(6): 576-81.