Overview
In 2012, psocids (book lice) were discovered in the Te Papa herbarium by Te Papa staff.
Climate testing at the time was tracking temperature at 21 degrees celcius and 59% relative humidity (RH).
Te Papa staff observed that psocids can cause damage sufficient to render some specimens worthless in a matter of two to three years. The before and after images for specimen SP087759/B show the scale of damage.
Alll specimens that had psocids present (approximately 30) were treated by freezing. It has not been possible to check the entire collection for psocids.
Specimens that suffered the most damage were recent collections, from 2008 onwards. In 2014, Te Papa staff observed some specimens with large numbers of psocids (50-100) on one sheet.
Te Papa received advice from other New Zealand herbaria who had overcome psocid issues. Two institutions advised that reducing the relative humidity (RH) below 50% would eliminate booklice by preventing their reproduction. This was supported by some internet resources.
In 2015, Te Papa invested in an improved climate control system, made up of heat pumps, dehumidifiers and sensors to acheive the desired lower relative humidity.
The Te Papa herbarium is now acheiving RH of 48% with temperature constant at 20 degrees celcius. Psocid monitoring continues.