Entomology (Study of Bugs)/Beetle in UK


UK Beetle by wooden door frame
UK Beetle by wooden do  

UK beetle by wooden door frame
UK beetle by wooden do  
Dear Ed,
We have just bought a new house which has been empty for 9 months. We found some beetles (see image) which are 7-10mm in length, and dark brown/ almost black. They have lines of dimples down their abdomen, and their thorax has a some dimpling but in a random pattern. They are under the parquet flooring in a living room next to a damp and rotting sill beneath a french patio door. The previous owner tells us that ants come through the gaps around the door, and I have found evidence of a couple of woodlice under some of the parquet. We are hoping these beetles are predators on the ants/ woodlice and can be left to continue their business, rather than a wood-boring type of beetle. Can you help us to identify them, because most beetles that look similar seem to be shorter in the reference books. By the way the back doesn't appear to be hairy to us (thought it was maybe a silken fungus beetle). The fibres in the picture are dust from the floor of the house I think rather than hairs! Regards, Matthew

Dear Matthew - First off, let me assure you that neither of these beetles will harm sound wood in any way. The first one is a ground beetle (Coleoptera: Carabidae), the vast majority of which are general predators on other small arthropods, and thus usually considered beneficial. The second one appears to be a darkling beetle (Coleoptera: Tenebrionidae) - see http://tinyurl.com/d9heygy for an example. Ones like these often are found in very damp/decaying wood, but it is unclear whether they are feeding on the decomposing wood or on something (fungi, other arthropods, etc.) within the wood. You probably could find other examples by peeling loose bark from downed logs or long-dead trees.

Hope this helps,

Entomology (Study of Bugs)

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Ed Saugstad


Will accept most questions in general entomology, including those related to medical entomology, taxonomy, ecology, arthropod surveillance, and pest management. If you are requesting a 'mystery bug' identification, PLEASE either attach an image to your question, or post an image on a web page (such as Flickr) so that I can look at it, as verbal descriptions frequently are insufficient for a definitive identification.


21 years in the U.S. Army as a medical entomologist; duties varied from surveillance of pest populations (including mosquitoes, cockroaches, ticks, and stored products pests) to conducting research on mosquito-virus ecological relationships and mosquito faunal studies. Ten years as a civilian analyst for the Department of Defense, primarily on distribution of vector-borne diseases worldwide. Limited experience on surveillance of agricultural insects in North Dakota and Indiana.

Entomological Society of America, West Virginia Entomological Society, Society for Vector Ecology, National Speleological Society, West Virginia Association for Cave Studies.

American Journal of Public Health, Contributions of the American Entomological Institute, Japanese Journal of Sanitary Zoology, Journal of Economic Entomology, Mosquito News, and Mosquito Systematics.

B.S. in entomology from North Dakota State University in 1963, M.S. in entomology from Purdue University in 1967.

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