The Odd Beetle

By Patrick Kelley, ACE

Funny and strange looking, the Odd Beetle (Thylodrias contractus) has been a frequent pest of museums with natural history collections since the early 1900’s in the United States. This pest that originated from central Asia is now well established in museums world-wide. It feeds mainly on the skins of animals in natural history collections and it will also attack dried insect specimens.

The reason that it is so “odd” is that the adult male and female appear to be two totally different insect species. The male looks like a slender beetle while the female is soft bodied and looks more like a louse. The adult male can fly and the adult female is wingless and
cannot fly. Both adults and larvae can reach up to 3 mm in size.

While the adult’s look so different from each other, the male and female in the larval form look nearly identical. They have hairy bands down their entire length and curl up when disturbed. They look similar in appearance to many other dermestid larvae to which they are related.

Although the pheromone for these beetles has been identified, it is not yet commercially available. The Larval Dermestid Monitors from Insects Limited will attract the larvae and give identification of an infestation. Once an infestation is found, it is best to treat with the standard treatment options for museum collections. You can view these at the website

Take some time now to familiarize yourself with this unique pest of museums and hopefully you won’t find yourself in an “odd” situation in the future. For more museum pest information, please visit


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