Insect Damage

Recognising the damage, identifying the cause and the insect responsible

Correctly identifying the insect responsible for damage is an essential first step to monitoring and trapping the offenders. Often however, no insect may be found and there is only damage to be observed such as holes in clothing and bare patches on carpets.

In other cases, adult insects may be found but it is the larval (caterpillar) stage that does the damage and so seeing or catching the adults can be an early indication of future damage likely to appear.

The following table provides a quick assessment of some of the most common places that damage may be observed and how to determine which pests are responsible

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Damage

Ragged ‘messy’ holes with silk-like threads and pinhead size balls of frass (the same colour as the fabric).

The Culprit

Webbing Clothes Moth larvae – small, white larvae with dark heads.

Adults

Small, silvery-gold moths often running over the material.

Webbing Clothes Moth (Tineola bisselliella)

Damage

Ragged holes some ‘frass’ often small, cream-coloured pupae cases resembling flattened grains of rice.

The Culprit

Case-bearing Clothes Moth larvae, white with dark heads.

Adults

Same as Webbing Clothes Moth, but darker wings.

Case-making Clothes Moth (Tinea pellionella)

Damage

Small ragged holes, no frass often ‘cast skins; (small, bristly brown shells).

The Culprit

Carpet Beetle larvae (woolly bears) – small brown hairy larvae, active.

The Adult

Small, oval beetles (like tiny ladybirds) with coloured patterning.

Varied Carpet Beetle (Anthrenus verbasci)

Damage

Small ragged holes, no frass often ‘cast skins; (small, bristly brown shells).

The Culprit

2-Spot Carpet Beetle larvae, as left, but with long bristly ‘tail’.

The Adult

Small, shiny, black oval beetle with two white spots on its back.

Two-Spot Carpet Beetle or Fur Beetle, (Attagenus pellio)

Damage

Grazed areas on paper with small holes, minute teeth marks visible around holes.

The Culprit

Silverfish: Small, thin silvery fast-moving insects. They avoid the light.

The Adult

Associated with damp, dark areas. 

Damage

Grazed areas on paper and bindings.

The Culprit

Book lice: Pinhead sized grey-brown insects. Fast moving and avoid light.

The Adult

Associated with damp, dark areas. 

Damage

Small (2-3mm) holes with pale insides. Often pale, gritty frass coming out.

The Culprit

Furniture beetle (woodworm) larvae.  Seldom seen.

The Adult

Small, brown, slim beetles (4-6mm long) with grooved wing cases and hooded head.

Damage

 Large (4mm) holes in oak, often with reddish, gritty frass.

The Culprit

Deathwatch beetle larvae.  Seldom seen.

The Adult

Smallish, fat beetles, grey-brown with lighter patches on wing cases and hooded head.  Often found on the floor below oak beams etc.

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