Silverfish clean homes but can signal hidden moisture

Silverfish are useful household insects that feed on mould and other organic debris, but a sudden increase in their numbers can indicate hidden moisture, ORF reported.

The small, silver-coloured insects are commonly found in bathrooms, toilets, kitchens and cellars, where they prefer cool, humid conditions. Their wriggling movements resemble those of small fish, while their metallic colouring inspired their name, according to nature conservation expert Carolina Trcka-Rojas.

Natural cleaning crew

Trcka-Rojas does not consider silverfish pests. They feed on skin cells, dead hair, wallpaper paste and mould, acting as a natural cleaning crew in hard-to-reach places. They do not damage buildings or property and can also be found in clean homes, often hiding in small cracks.

Silverfish avoid light and usually appear in darkness. Seeing them after switching on a light does not necessarily indicate an infestation.

Possible sign of moisture

If 20 to 50 silverfish suddenly become visible, however, this may indicate that moisture is accumulating somewhere. Dampness can soften wallpaper or wood and lead to mould, which silverfish readily eat. Once the damp areas have been dealt with, the large population should disappear on its own.

Silverfish have two related species with different habits. Oven fish are often found in kitchens near ovens or in heating rooms, where temperatures are higher. They feed on dust, waste particles and dead members of their own species, Trcka-Rojas said.

Paper fish are more unwelcome because they prefer cellulose and can eat paper, cardboard and wallpaper. They are attracted particularly to waste paper and scraps. In larger numbers, they can damage old documents and books, according to the expert from the conservation association.