Indicator Species For Identifying Hidden Construction Damage In Historic Buildings

Hidden damages that develop over long periods of time and remain undetected, may cause immense loss. An externally visible settlement of species whose presence draws attention to damage inside the structure can give hints to this hidden damage. In a castle in North Rhine-Westfalia (Germany) which was built in the 13th century, an infestation of Lasius brunneus (Formicinae) was found below a crack in the middle of an oak ceiling beam. Research into the history of the castle revealed that several renovations were carried out during the following centuries. The ants’ remains below the beam contained pieces of captured insects, empty pupae cases, and large amounts of typical lens-shaped droppings of Xestobium rufovillosum (Ptinidae). The young larvae of X. rufovillosum require wood that is rotten by fungus. This led to the finding that the interior of the beam was affected by fungal infestation followed by woodworm infestation and therefore no longer met the static requirements of a ceiling beam. Further investigations revealed that the building was hit by two bombs during World War II and that repairs were delayed. Similar cases of construction damage in cultural heritage which became apparent through the activity of ants were repeatedly found in the past.