Silverfish and Book Lice
Silverfish and book lice are common indoor pests, especially in damp environments. Although they cause little physical damage, they can cause severe superficial aesthetic damage. They are also indicators of high humidities and high moisture contents in materials. Outside they are found in birds’ nests and tree bark, while inside buildings they are found in damp secretive areas, such as behind skirtings, under wallpaper edges and in warm humid conditions that occur in bathrooms, kitchens, laundries etc. They avoid light and will move swiftly if disturbed.
Silverfish
Lepisma saccarina
Silverfish are primitive insects that are so named because of their silvery/grey colour and fash sinuous movements. The adults grow to about 12mm long and can live for several years. They lay eggs in dark, damp areas and these hatch into ‘nymphs’ which, as they grow through several moults, gradually gain the size, colour and attributes of the adults.
They feed mainly on carbohydrates found in starchy materials such as some foodstuffs, but can also digest cellulose (paper) and proteins from animal glues, dead insects etc. As these insects need high humidities and warm, damp conditions to thrive, their foodstuffs will often have been damaged or softened by microscopic moulds on which they will graze. Wallpaper, books and works of art on paper can be extensively damaged in this way.
Book lice are not true lice but small (1-2mm) wingless insects that feed on microscopic moulds and fungi, growing on damp material such as book bindings, upholstered furniture and foodstuffs. Because their life cycle is relatively short and many eggs are laid by the females, large infestations can rapidly build-up in warm, humid conditions.
Book Louse
Psocid
Book lice are not true lice but small (1-2mm) wingless insects that feed on microscopic moulds and fungi, growing on damp material such as book bindings, upholstered furniture and foodstuffs.
Because their life cycle is relatively short and many eggs are laid by the females, large infestations can rapidly build-up in warm, humid conditions.
How to control them?
As both silverfish and psocids need warm, humid conditions to thrive, lowering temperatures and humidities is an obvious control method to prevent attacks from occurring and arresting active ones.
Increased ventilation of areas, dehumidifiers etc., to bring relative humidities down will kill the microscopic fungi on which book lice feed and help to control silverfish.
In inaccessible areas, where the insects may be harbouring, such as under skirtings and in cracks in building structures, desiccant dusts are useful. These are inert, non-toxic, fine dry dusts which absorb the protective waxy coating around insects allowing them to dry out and die. They are applied lightly with a puffer into cracks and crevices. An appropriate dust mask and gloves should be worn, as the dusts are an irritant.
Insecticide sprays are rarely effective.