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 in UK homes are increasingly responsible for widespread infestations and damage to paper, books, wallpaper, and stored items, often in rooms homeowners would never expect to find them.
Contents
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 Grey Silverfish Are Spreading in UK Homes
Grey silverfish were rarely recorded in the UK before the 2000s. Their spread is linked to several changes in how homes are built and heated. Modern insulation, draught-proofing, and central heating systems create stable indoor temperatures year-round, which suits grey silverfish far better than the traditional silverfish that depends on seasonal moisture. Homes with underlying damp or condensation problems can be particularly vulnerable, as these conditions support both species simultaneously.
Unlike common silverfish, which tend to stay close to sinks, showers, and other moisture sources, grey silverfish can establish themselves throughout an entire property. They hide inside wall voids, beneath floorboards, and behind skirting boards, areas that are rarely disturbed and difficult to treat without professional access.
If you’re seeing silverfish activity mainly around bathrooms or kitchens, common silverfish are often responsible, particularly in older properties with condensation or ventilation issues. If sightings are spread across multiple rooms, or you’re finding damage in dry areas, grey silverfish are the more likely cause. For bathroom infestations specifically, see our guide to silverfish in bathrooms and how to get rid of them.
Bugwise regularly treats grey silverfish infestations across East London and Essex — commonly in Victorian terraces in Ilford and Dagenham, purpose-built flats in Romford, and older housing stock across Barking and Hornchurch, where cavity walls and suspended floors provide ideal harbourage conditions.
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.
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. Based on treatment work carried out by Bugwise technicians across London and Essex, DIY methods rarely achieve lasting control because the infestation is rarely limited to one accessible area.
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 do not 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.
Worried About Silverfish in Your Home?
Our expert team provides fast, discreet silverfish treatment services across London and Essex. All treatments come with a 30-day guarantee, and we’re available for same-day bookings — including weekends and evenings.
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.
Frequently Asked Questions
Grey silverfish (Ctenolepisma longicaudata) are larger, reaching 15–20mm, and can survive in dry conditions throughout a property — including bedrooms, living rooms, and hallways. Common silverfish (Lepisma saccharina) are smaller, typically 10–15mm, and stay close to damp areas such as bathrooms and kitchens. Grey silverfish also have longer antennae, a fringe of bristles along the body, and reproduce efficiently at lower humidity levels, making them harder to control.
Yes. Grey silverfish are significantly harder to eliminate because they are not confined to damp rooms, lay eggs deep inside cracks and structural voids, and tolerate the drier conditions found throughout most UK homes. DIY sprays and humidity reduction — which can help with common silverfish — are rarely sufficient. Professional treatment with targeted residual insecticide and harbourage identification is usually required to achieve lasting control.
In most cases, yes. Because grey silverfish can spread throughout an entire property rather than staying in one room, the potential for widespread damage is greater. Both species feed on starch, organic dyes, and gelatine-based materials, but grey silverfish are more likely to reach stored books, documents, wallpaper, and archived items in dry areas of the home that common silverfish would not normally access.
Yes. Both species feed on paper, cardboard, wallpaper paste, organic inks, and the gelatine binding used in book spines. Damage typically appears as thinned or translucent patches on paper surfaces, irregular holes with weakened edges, and areas where ink has been selectively eaten away. Flock wallpaper is particularly vulnerable. Over time, this damage is irreversible, which is why early treatment matters — especially where grey silverfish are present.
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