Grey Silverfish vs Common Silverfish

Grey silverfish are becoming far more common in UK homes, and they behave very differently from traditional silverfish. Knowing the difference is key to stopping damage early and choosing the right treatment.

What Is the Difference Between Grey Silverfish and Common Silverfish?

Grey silverfish are larger, more adaptable, and able to survive in dry areas, while common silverfish are smaller and usually limited to damp spaces like bathrooms and kitchens.

Grey silverfish (Ctenolepisma longicaudata) can spread throughout entire homes, including living rooms, bedrooms, and storage areas. In contrast, common silverfish (Lepisma saccharina) tend to stay close to moisture sources.

Because they tolerate lower humidity and reproduce efficiently indoors, grey silverfish are increasingly responsible for widespread infestations and damage to paper, books, wallpaper, and stored items in UK homes.

Key Facts: Grey Silverfish vs Common Silverfish

Feature	Common Silverfish	Grey Silverfish
Scientific name	Lepisma saccharina	Ctenolepisma longicaudata
Typical size	10–15mm	15–20mm
Preferred environment	Damp rooms	Can tolerate dry environments
Common locations	Bathrooms, kitchens	Bedrooms, living rooms, hallways
Damage risk	Moderate	Higher due to wider spread
Spread in UK	Long established	Increasing rapidly

Silverfish infestations in UK homes are becoming more persistent — and in many cases, more destructive. While most homeowners are familiar with the common silverfish, a newer and more aggressive species known as the grey silverfish is now spreading rapidly across the UK.

Understanding the difference matters. Grey silverfish behave differently, tolerate drier conditions, and pose a higher long-term damage risk if left untreated.

This guide explains how to tell them apart, why infestations are increasing, and when professional silverfish treatment becomes essential.

Why UK Homes Are Seeing More Silverfish Damage

Silverfish infestations in UK homes are becoming more persistent — and in many cases more destructive — due largely to the spread of grey silverfish.

While most homeowners are familiar with the traditional silverfish species found in damp areas, grey silverfish behave very differently. They tolerate lower humidity, hide deep inside structural voids, and can infest entire properties rather than remaining confined to bathrooms or kitchens.

Understanding the difference between these two species is important because it affects how infestations spread — and how they should be treated.

This guide explains:

• how to tell grey silverfish apart from common silverfish
• why infestations are becoming more common in UK homes
• what type of damage silverfish can cause
• when professional silverfish treatment becomes necessary

If you’re seeing activity mainly around sinks, showers, or toilets, the common silverfish is often responsible — particularly in properties with condensation or ventilation issues.

Many homeowners first notice infestations in bathrooms, where moisture creates the ideal environment for silverfish to thrive. If this sounds familiar, read our guide to silverfish in bathrooms and how to get rid of them.

Grey Silverfish (Ctenolepisma longicaudata)

Grey silverfish are a larger, newer species that has only recently become established in the UK — and they’re spreading fast. They are increasingly responsible for infestations in living rooms, bedrooms, and hallways, not just bathrooms.

Distinctive features include:

• Larger size: 15–20mm long
• Grey, sometimes blotchy scales
• A fringe of short bristles along the head and body
• Antennae longer than the body
• Much longer rear bristles than common silverfish

Crucially, grey silverfish can breed and cause damage at lower humidity levels, making them far harder to control with DIY methods alone silverfish-and-grey-silverfish.

Why Grey Silverfish Are a Bigger Problem in Modern Homes

Unlike traditional silverfish, grey silverfish don’t rely solely on bathrooms or cellars.

They can survive and reproduce in:

• Living rooms
• Bedrooms
• Hallways
• Storage cupboards
• Office environments

This adaptability is why they pose a greater risk to books, wallpaper, labels, artwork, and stored items, even in homes that appear dry and well-ventilated. Many homeowners first notice them while trying to identify and get rid of silverfish but struggle because the infestation isn’t limited to one damp room.

What Damage Do Silverfish Actually Cause?

Silverfish don’t bite and aren’t dangerous to humans — a point we explain in detail in what are silverfish and can they hurt you? — but the damage they cause to property and belongings is often underestimated.

Industry Insight

According to the British Pest Control Association, silverfish are usually considered nuisance pests, but large infestations can still create serious problems in certain environments.

“Although this pest is mostly only considered a nuisance, if they reach substantial numbers they can become unacceptable, especially in sterile environments such as hospitals. They can also damage papers, textiles and packets of dried food in damp kitchens.”

In practice, pest controllers often see this damage in stored paperwork, books, wallpaper paste, and archived materials where infestations are allowed to persist.

Materials Commonly Attacked

According to the fact file, silverfish damage includes:

• Paper, books, documents, and photographs
• Wallpaper (especially flock wallpaper)
• Wallpaper paste
• Labels and prints
• Organic inks
• Occasionally silk and other delicate textiles silverfish-and-grey-silverfish-…

They are particularly attracted to starch, gelatine, organic dyes, and microscopic mould, which explains why older properties and stored items are often affected first.

Signs of Silverfish Damage

Typical damage patterns include:

• Scratched or thinned paper surfaces
• Translucent patches on books or documents
• Irregular holes with weakened edges
• Areas where ink has been selectively eaten

Over time, this damage becomes irreversible, especially in stored collections or decorative finishes silverfish-and-grey-silverfish.

What Does a Silverfish Infestation Look Like?

Common Signs Include:

• Fast-moving insects when lights are switched on
• Sightings in bathrooms, kitchens, or along skirting boards
• Damage to books, wallpaper, or stored paperwork
• Cylindrical frass (droppings) larger than those from many other insects

Nymphs are rarely seen because they live close to food sources and harbourage areas, but they resemble small, translucent adults silverfish-and-grey-silverfish.

Why DIY Treatments Often Fail

Reducing humidity can help with common silverfish — but it is not enough for grey silverfish.

DIY sprays and traps often fail because:

• Eggs are laid in hidden cracks and voids
• Nymphs develop close to food sources
• Grey silverfish tolerate drier environments
• Surface sprays don’t reach harbourage areas

Without professional inspection, infestations often appear “gone” temporarily — only to resurface weeks later.

Professional Silverfish Treatment: When to Act

You should consider professional treatment if:

• Silverfish are seen outside bathrooms or kitchens
• Damage continues despite improved ventilation
• Traps show ongoing activity
• Grey silverfish are suspected due to size and behaviour

Professional treatment focuses on targeted residual application, harbourage identification, and environmental advice — not just visible insects. For full details, see our silverfish treatment service.

Prevention: What Actually Works

Based on the biology of both species, effective prevention includes:

• Reducing humidity where possible
• Eliminating microscopic mould and food residues
• Sealing cracks, voids, and wall gaps
• Protecting stored paper items and books
• Professional monitoring where grey silverfish are present silverfish-and-grey-silverfish-…

For grey silverfish, professional intervention is often the only reliable solution.

Final Word: Why Early Action Matters

Silverfish infestations rarely resolve themselves — and grey silverfish make the problem more complex.

The longer an infestation is left untreated, the greater the risk of:

• Widespread internal damage
• Repeated re-infestation
• Costly replacement of damaged items

If you’re seeing silverfish activity beyond damp areas, it’s time to take it seriously.

Bugwise Pest Control provides targeted silverfish treatments across London & Essex, backed by professional inspection and long-term control strategies.