Advice
Silverfish and grey silverfish: how to recognise, understand and get rid of them
Silverfish are elongated, silvery, shiny insects with three tail bristles. They are active at night and avoid light, which is why you usually only see them when you switch on the bathroom light at night. Nibbled paper, wallpaper and fabrics give them away. They breed slowly but do not go away on their own. Lower the humidity and seal the cracks, and you take away what the infestation depends on.
In this article
Straight to the solution: Get rid of silverfish or go directly to the Super Ninja Silverfish Trap.
What is the difference between silverfish and grey silverfish?
Both are elongated and silvery; the grey silverfish (Ctenolepisma longicaudata), also called the long-tailed silverfish, is slightly larger, greyish to brownish and hairier. Common silverfish need high humidity and live mainly in bathrooms and kitchens. Grey silverfish cope with dry air too, so they also turn up in living rooms, bookcases and archives.
Which kind of silverfish am I most likely to have at home?
Most likely a grey silverfish. In recent infestations in the Netherlands, around 95% of cases involved the grey silverfish (Ctenolepisma longicaudata), not the common silverfish. That explains why you also find them in a dry living room or bookcase.
What attracts silverfish and where do they come from?
Moisture, warmth and food: mould, skin flakes, hair, crumbs and starchy materials such as paper, wallpaper paste and book glue. They often come in with removal boxes, books or clothes and live in cracks, behind skirting boards and behind wallpaper.
How long can a silverfish survive without food?
Surprisingly long: grey silverfish survive more than 250 days without food. Leaving nothing lying around for a few weeks is therefore not enough. What does work is lowering the humidity. Grey silverfish cope with dry air better than the common silverfish, but they too avoid rooms with less than 50% humidity.
How fast do silverfish breed?
Slowly, but they live a long time. A grey silverfish lays around 56 eggs a year, spread over small batches of 2 to 20 eggs in cracks. These eggs only hatch at a humidity of at least 55%. A grey silverfish takes about two years to become an adult, and it can live for up to eight years. So an infestation grows slowly, but it does not go away on its own either.
Do silverfish eat clothes?
Yes, grey silverfish in particular. They feed on fabrics that contain starch or dirt, such as cotton, linen and viscose, and above all on clothes that have not been washed for a while. Typical signs are small feeding marks and scraped patches rather than round holes. Clothes stored for a long time in a damp wardrobe or box are most at risk.
Are silverfish harmful or dangerous?
Not to people: they do not sting or bite and do not transmit any known diseases. They can, however, damage paper, books, photos, wallpaper and fabrics. Lots of silverfish are also a sign of too much moisture or mould in the house.
How do you get rid of silverfish?
First bring the humidity below 50%, and the infestation stops growing. At the same time, put silverfish traps where they run. That way you see how big the infestation is and catch them without spraying.
Lay the trap flat against the skirting board, behind the toilet or under the washbasin: warm, damp spots they run past at night. The attractant is in the glue itself. Replace the trap when it is full or after three months.
How do you prevent silverfish?
- Lower the humidity. Ventilate after showering and do not dry washing indoors.
- Seal joints and cracks. Close gaps at skirting boards, tiles and pipe openings with sealant.
- Remove food sources. Vacuum regularly, wipe away crumbs and keep paper, books and boxes dry.
- Check what you bring in. Shake out or vacuum removal boxes, second-hand books and clothes before putting them away.
Source: literature study by Wageningen University & Research for Super Ninja (2020), citing Schoelitsz.
