Pest Lexicon – Green Guardia

Gray silverfish: Identifying & sustainably reducing silverfish-like insects

Gray silverfish look similar to common silverfish, but are often active in drier living areas – for example in bedrooms, hallways or studies. They feed on starchy materials such as paper, paste and dust particles. Here you can find out how to reliably identify gray silverfish and get the cause under control permanently.

ⓘCtenolepisma longicaudata · Gray silverfish #Gray silverfish in the house · Feeding marks on paper

What are gray silverfish?

Gray silverfish (also known as long-tailed silverfish) are wingless insects from the Zygentoma group. Unlike classic silverfish, gray silverfish are often longer, climb better and feel at home not just in the bathroom, but also in dry rooms. They are nocturnal and hide during the day in cracks, behind baseboards or in cardboard boxes.

Zygentoma often in dry rooms nocturnal

Important: Gray silverfish are often a sign of many hiding places (cracks, cardboard boxes, paper storage) and a permanent food supply (dust, paper, paste). The sooner you react, the easier it is to reduce the population.

How to recognize an infestation

fast, silvery-gray "fish", usually visible at night
often in dry rooms: hallway, bedroom, office, storage room
small feeding marks on paper, cardboard, wallpaper edges or book covers
often: molting remains (fine, transparent "skins")

Green Guardia Tip: Place a piece of cardboard or paper against the wall edge in the evening – in the morning you can check for activity (or use monitoring traps).

What is attacked?

Paper, cardboard, books, files
Wallpaper paste, labels, cardboard packaging
starchy residues (e.g. crumbs, dust)
Textiles with sizing/finish (rare, usually incidental feeding)

Why does an infestation occur?

many hiding places: cracks, baseboards, cavities
lots of paper/cardboard (storage, moving boxes)
long-term stable room climate (they are very adaptable)
lack of monitoring in rarely used areas

What to do if there is an infestation? (natural & sensible)

1. Reduce hiding places

Seal cracks and joints (baseboards, plinths, wall connections)
Avoid cardboard boxes or store them in airtight boxes

2. Cleaning & order

vacuum thoroughly (edges, baseboards, under furniture)
reduce dust and crumbs (minimize food source)

3. Use monitoring

Glue traps help to detect and reduce activity
Place traps along walls/baseboards

Why gray silverfish can be so persistent

Gray silverfish are adaptable and can go a long time without much food. If there are many hiding places, they often go unnoticed. Sustainable success is therefore usually achieved through a combination of sealing, cleaning and monitoring.

Why this works: Fewer hiding places + less food + targeted control = significantly fewer gray silverfish – and you prevent the population from rebuilding.

FAQ about gray silverfish

What is the difference to silverfish?

Gray silverfish occur more frequently in dry rooms, are often slightly larger and can spread better throughout the home than classic silverfish.

Why do I only see them at night?

Gray silverfish are nocturnal and hide during the day in cracks, behind baseboards or under furniture.

Does airing out help against gray silverfish?

Airing out can help, but is often not the main lever against gray silverfish. Sealing, cleanliness and monitoring are more important.

How can I prevent them?

Avoid cardboard boxes, store paper in a dry place, vacuum regularly and seal cracks – especially in storage rooms and along baseboards.