A number of terms exist to describe waste material from creatures – droppings, faeces or dung to the more colourful ‘cow pies’ or ‘road apples’ used to describe cattle and horse excrement respectively.
Frass however, is not an everyday term you tend to hear. Dictionary descriptions claim it’s derived from the German past tense of fressen, which means ‘to gobble or to feed as an animal might’. The English usage derives from the idea of excrement from food that larvae have eaten – debris or excrement produced by insects.
This frass can be used to help identify woodworm pests even if the adult insects are no longer visible, as different species form different shaped droppings. The frass of wood-boring beetles is made up of fragments torn off but not consumed, and fragments that have passed through the insects gut! It resembles a fine, powdery dust and is usually found below the area of the infected wood. Frass falls out of old flight holes, when larvae bore through old larval tunnels, hence the build up of material below the infested timber. It is not generally a result of new adult beetles emerging.
Woodworm refers to the larvae of any wood-boring beetle, rather than just one particular species. In the UK, the most common woodworm larvae are from the Common Furniture Beetle, Deathwatch Beetle, House Longhorn Beetle and Powderpost Beetle.
Wooden items or structural timbers within a property can be infected with eggs or larvae of wood-boring beetles without it being noticeable. You may not discover a woodworm infestation for quite a while, as larvae continue to tunnel and feed in wood for several years. As the larvae mature and increase in size, they bore towards the wood surface to pupate and emerge as adult beetles.
There are some other tell-tale signs (apart from frass) that you can look for if you think there may be a woodworm problem in your property:
- Frass (also known as bore dust) – usually visible below the infested timber.
- Flight holes in timber – round or oval in shape with sharp edges.
- Crumbling wood – around corners or edges to roof joists or floorboards.
- Adult beetles – emerging from timbers usually between April and September or dead beetles found near the infected timber or on nearby window sills.
Not all of these signs of activity may be cause for concern. It’s possible that holes and frass might just indicate a previous woodworm infestation, long since dead. A good tip is to block any suspect holes during the winter by painting over them, applying masking tape or using wax to coat the holes and surrounding area. In the spring, you can check if any beetles have chewed through and emerged, indicating a live infestation.
To confirm whether you have a serious, current woodworm problem it’s important to consult a professional Certificated Surveyor in Remedial Treatment (CSRT) to identify the woodworm species and recommend the most suitable treatment.