Silverfish usually show up at night in the bathroom, the kitchen or the cellar. They like dark and damp and live on starch: wallpaper paste, paper, cardboard and plant fibres. By day they hide in cracks, behind skirting boards and under the washing machine.
A trap catches the ones already indoors and shows where they run. The lure is worked into the glue and the trap is made from 92 % recycled material. Put it where you see them: against the skirting, behind the toilet, under the basin. Replace it when full or after three months. Reduce the humidity as well, because that is ultimately what keeps them inside.
Do silverfish go for clothes?
Yes, but differently from clothes moths. Silverfish feed on plant fibres such as cotton, linen and viscose, and especially on textiles carrying starch or sweat residue. Wool and cashmere they usually leave alone, and that is precisely what clothes moths do attack. If you find irregular holes or grazed patches in cotton that sat for a long time in a damp cupboard, they are the likely culprit.
Where do silverfish lay their eggs?
Tucked deep into cracks, seams and crevices where you cannot see them. A female lays them in small batches over a long period. They only hatch when it is damp enough, which is why a silverfish problem in a dry room dies out on its own.
How quickly do they reproduce?
Slowly, compared with most insects. A silverfish matures sluggishly and can live several years. Against that, it keeps laying throughout those years. If you see one there are almost always more, but you will not get a sudden explosion the way you do with fruit flies.
Where do they come from?
They rarely walk in from outside. Usually they are already there, hidden in seams and cracks, and a damp room keeps them alive. A poorly ventilated bathroom, a leaking pipe or a cold outside wall with condensation is enough.
Are silverfish dangerous?
No. They do not sting or bite and carry no disease. The damage is material: books, photographs, wallpaper and textiles. The real nuisance is that a large population is hard to clean away.
How to tackle it
Put traps along the skirting and check for two weeks where most of them are. Then deal with the cause: ventilate the bathroom better, fix leaks, seal cracks around pipes and skirting. Without damp they disappear on their own, with damp they always come back.