What Does Woodworm Look Like?

Woodworm is a term used to describe the larvae of several species of wood-boring beetles that feed on and tunnel through timber.

In the UK, woodworm infestations can damage everything from antique furniture to roof timbers.

But what does woodworm look like?

And how can you tell which type you’re dealing with?

Let’s break it down by first understanding the general signs of woodworm, followed by a detailed look at the most common species found in UK properties.

What Does a Woodworm Look Like in General?

Woodworm refers to the larval stage of wood-boring beetles.

The larvae themselves are small, creamy-white grubs with curved, segmented bodies and tiny brown heads.

They are usually 2–7mm long and are rarely seen unless timber is broken open.

More commonly, you’ll spot evidence of their presence, which includes:

• Tiny round exit holes (1–2mm in diameter) on wood surfaces
• Fine, powdery dust (frass) around holes or beneath affected wood
• Tunnels (galleries) inside the wood if it is split or broken
• Crumbling edges, weakened floorboards or beams
• Adult beetles, particularly in warmer months

Read more here: 👉 How to Identify and Get Rid of Black Carpet Beetles

Types of Woodworm and What They Look Like

Different types of woodworm come from different species of beetles.

Each has unique features in terms of physical appearance, preferred habitat, and visible signs of infestation.

1. Common Furniture Beetle (Anobium punctatum)

The Common Furniture Beetle is the most widespread woodworm in the UK.

Its larvae are small, creamy-white, and C-shaped, measuring around 2–5mm long.

The adult beetle is brown, dome-shaped, and about 2.5–4.5mm in size.

It creates tiny round exit holes (1–2mm) and leaves behind fine, gritty frass.

It prefers softwoods like pine and is commonly found in floorboards, joists, loft timbers, and furniture, especially in damp or poorly ventilated areas.

Appearance (Larvae):

• Cream-coloured, C-shaped body with a darker head
• Around 2–5mm long
• Narrow, rigid body segments

Appearance (Adult Beetle):

• Brown, dome-shaped body
• 2.5–4.5mm long
• Fine hairs on the back, giving it a dusty look

Habitat:

• Prefers softwoods like pine and spruce
• Found in floorboards, joists, furniture, and loft timbers

How to Identify:

• Exit holes are 1–2mm in diameter
• Powdery frass may fall when tapping or disturbing the timber
• Common in damp, poorly ventilated areas

2. Deathwatch Beetle (Xestobium rufovillosum)

The Deathwatch Beetle is a wood-boring insect that primarily attacks damp, decaying hardwoods like oak and elm.

The larvae are up to 11mm long, creamy-white, and live deep inside timber for several years.

The adult beetle is brown and mottled, measuring 7–9mm, and is famous for its ticking sound during mating season.

You’ll typically find it in older, historic buildings with fungal decay. Look for larger exit holes (3–4mm) and coarse, gritty frass near timbers.

Appearance (Larvae):

• Up to 11mm long
• Creamy-white, wrinkled body with brown jaws

Appearance (Adult Beetle):

• Brown and oval-shaped with mottled patches
• 7–9mm in length
• Known for making a “ticking” sound during mating season

Habitat:

• Attacks hardwoods like oak and elm, particularly when decayed by fungal rot
• Found in historic buildings, churches, and older properties

How to Identify:

• Larger exit holes (3–4mm)
• Frass is coarse and sausage-shaped
• Most damage occurs deep inside beams, often not visible externally

3. House Longhorn Beetle (Hylotrupes bajulus)

Read more here: How to Prevent Carpet Beetle Infestation

The House Longhorn Beetle is one of the most destructive wood-boring insects found in the UK, though it’s primarily confined to southern England, especially Surrey.

The adult beetle is large (10–25mm), dark brown or black, with distinctive long antennae, often longer than its body, and white speckles on its wing cases.

Its larvae are cream-coloured, robust, and can grow up to 30mm, making deep tunnels in softwood timbers.

You’ll often find this beetle in roof timbers like pine, where it leaves behind large oval exit holes (6–10mm) and coarse, gritty frass.

Due to the severe structural damage it can cause, identifying and treating this beetle promptly is critical.

(Mainly found in parts of southern England, especially Surrey)

Appearance (Larvae):

• Up to 30mm long
• Creamy-white with strong mandibles and prominent ridges on the body

Appearance (Adult Beetle):

• Black or dark brown with white/grey speckles
• 10–25mm in length
• Long antennae (often longer than the body)

Habitat:

• Targets softwoods, especially roofing timbers like pine
• Thrives in warmer environments (lofts, attics)

How to Identify:

• Large oval exit holes (6–10mm)
• Frass looks coarse, gritty, and contains wood fragments
• Structural weakening is often severe in advanced stages

4. Powderpost Beetle (Lyctus brunneus)

The Powderpost Beetle is a small but destructive wood-boring insect that primarily targets new hardwoods such as oak, ash, and mahogany, often within 10 years of being milled.

The adult beetle is slender, reddish-brown, and measures just 2–5mm long, with a narrow, elongated body that can squeeze into tiny cracks.

The larvae are equally small and hard to spot, typically about 1–2mm, making infestations difficult to detect in the early stages.

These beetles produce very fine, talcum-powder-like frass and tiny, 1mm exit holes, usually found in wooden floors, furniture, or kitchen units.

Though small, they can cause significant surface damage to new timber products if not treated quickly.

See our other guide: 👉 What Is Woolly Bear Carpet Beetle?

Appearance (Larvae):

• Around 1–2mm long
• Very slender and hard to spot

Appearance (Adult Beetle):

• Reddish-brown, narrow and elongated body
• 2–5mm long

Habitat:

• Infests hardwoods like oak, ash, and mahogany
• Common in recently manufactured furniture or imported timber products

How to Identify:

• Very fine exit holes (1mm)
• Frass is very powdery, like talcum powder
• Affects newer timbers less than 10 years old

Final Tips for Identification

• Time of Year Matters: Adult beetles usually emerge from wood between April and September, which is when you’re most likely to spot them or find fresh exit holes.
  
• Check for Activity: Fresh frass, beetles, or damp conditions may suggest an active infestation, while older exit holes could be historic and inactive.
  
• Use a Magnifying Glass: Helps to examine hole size, frass texture, and beetle features more closely.
  
• Don’t Rely on One Sign: Use a combination of clues (exit holes, frass, structural damage, and beetle sightings) for accurate identification.

When to Call a Professional

If you spot signs of woodworm and are unsure about the extent of the damage or the species involved, it’s best to consult a professional.

Misidentifying a species like the House Longhorn Beetle could lead to severe structural risk if left untreated.

🔗 You can find certified timber pest specialists through the Property Care Association (PCA)

Would you like me to create a downloadable comparison chart or infographic for visual identification of these beetles?

Woodworm Comparison Table (UK)

Woodworm Type	Larvae Appearance	Adult Beetle Appearance	Preferred Timber	Exit Hole Size	Frass Texture	Common Habitat
Common Furniture Beetle (Anobium punctatum)	Creamy-white, curved, 2–5mm long Brown head, ridged body	Brown, dome-shaped, 2.5–4.5mm Fine hairs on back	Softwoods (pine, spruce)	1–2mm	Fine, gritty, light powder	Furniture, floorboards, beams
Deathwatch Beetle (Xestobium rufovillosum)	Creamy, wrinkled, up to 11mm Brown jaws	Reddish-brown, narrow, 2–5mm Elongated body	Aged hardwoods (oak, elm)	3–4mm	Coarse, gritty, sausage-shaped pellets	Rotting timbers in old/historic buildings
House Longhorn Beetle (Hylotrupes bajulus)	Up to 30mm, strong jaws Prominent ridges	Large, dark brown/black, 10–25mm Long antennae, white speckles	Softwoods (roof timbers, pine)	6–10mm	Coarse frass, often in tunnels	Attics and lofts (mainly southern England)
Powderpost Beetle (Lyctus brunneus)	Slender, hard to spot, 1–2mm	Brown, mottled body, 7–9mm Oval-shaped	Hardwoods (oak, ash, mahogany)	~1mm	Extremely fine, talcum-powder-like	New hardwood furniture & flooring (<10 yrs old)

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