Frass and pest residue
The powder, cast skins and webbing left by something that has been eating the fibre. The deposit is the least of it: the material it came from has gone.
In detail
Frass is the conservator's word for the debris and excrement insects leave behind, and it is usually described as a soft powdery material. On a wool carpet or in a wardrobe it is accompanied by cast larval skins, fine webbing, scattered silken patches, and loss of pile or a trail of bitten fibres. It is listed as a contaminant because that is how a reader meets it — a deposit they want to remove — but it is the only entry here where removing the deposit is the smaller half. The powder lifts. The grazed fibre cannot be put back. Two observations make it identifiable without an entomologist, and both come from the same federal leaflet. The excreta takes the colour of the material it has been feeding on, so a deposit that matches the carpet exactly is not carpet dust. And the damage pattern is a trail of bitten fibres rather than a discrete hole, because the larva bites off a fibre, chews it and moves to the next. It appears where things are undisturbed and dark: folds, closets, attics, carpet pile under heavy furniture. CleaningHQ does not advise on pest treatment or species identification. What it can tell you is whether what you are looking at is dirt.
What works
Vacuum cleaner is effective against Frass and pest residue Supported
Named by the conservation literature as one of the jobs a vacuum is bought for.
Why
- Frass and pest residue is explained by Keratin digestion
- Frass and pest residue is explained by Damage versus soiling
Sources for this page
Sources
Conserve O Gram 3/11: Identifying Museum Insect Pest Damage
National Park Service, US Department of the Interior, 2008 · Government or regulator
Relied on for: That frass is debris or excrement produced by insects, usually a soft powdery material; that cast skins, webbing and grazed surfaces accompany it; that the excreta takes the colour of the material fed on; and that the larva bites off a fibre and moves on, leaving a trail of damaged fibres. (states this directly)
Verification: a person has read the passage relied on.
Read on — 'Evidence of Pest Activity', 'Textile Pests', 'Clothes Moths' and 'Wood Pests'. Supports the claim as stated. Opens a class of question the catalogue could not previously take: whether the mark in front of the reader is a cleaning problem at all, or material that has already gone.
Last reviewed by a person on .