Silverfish
Should you kill silverfish or not?
You can kill a silverfish if you want to, but it does little good: for every silverfish you see, others are hiding with their eggs in cracks and joints, and as long as your home stays damp, new ones keep coming. If you want to get rid of silverfish, deal with the damp and catch them with a trap, so you can see where they come from.
In this article
Why shouldn't you kill silverfish in your house?
There is no rule or official advice against killing silverfish. People who say it usually mean one of three things: that killing them is pointless because there are more, that silverfish are useful because they eat mould and dead insects, or that you would spread their eggs. The first is true, the second only half true, and for the third there is no evidence, as you can read below.
Does killing a silverfish release its eggs?
There is no evidence for that: silverfish lay their eggs in batches in joints and cracks, not where you see them running. A grey silverfish lays on average 56 eggs a year, in batches of 2 to 20, which only hatch at a humidity of at least 55 %. The eggs that keep an infestation going are already hidden, whether you kill the insect or not.
Are silverfish good to have in the house?
Only slightly: besides starch, paper and wallpaper paste, silverfish also eat mould, mites and small dead insects. That does not make them cleaners worth keeping. They live on exactly what is going wrong in your home, damp and mould, and in large numbers they damage paper, books, wallpaper and clothes.
What should I do if I see one silverfish?
Treat one silverfish as a sign that part of your home is damp enough for them: a poorly ventilated bathroom, a leaking waste pipe, condensation under the sink or a damp wall. Silverfish avoid light and hide during the day, so if you see one at night there are often more. If you see them in a dry room or bookcase, it is probably a grey silverfish; read how to identify grey silverfish.
Is it better to vacuum silverfish than to kill them?
Vacuuming works better than killing them one by one, because along skirting boards and in corners you also remove food and dust and pull insects out of cracks. The literature names thorough, regular vacuuming as one of the ways to keep an infestation small. Empty the bag or bin outside afterwards.
What should you do instead of killing silverfish?
Deal with the cause and catch the ones already there, in four steps:
- Bring the humidity below 50 %: ventilate after showering, fix leaks and check it with a hygrometer.
- Seal joints and cracks at skirting boards, tiles and pipe openings.
- Vacuum often and clear piles of paper and cardboard.
- Put down a silverfish trap where you see them, so you know where and how many there are. Replace it when it is full or after 3 months.
The full approach is in our guide how to get rid of silverfish. A flat trap for the bathroom is in silverfish traps.
Sources: Kennis- en Adviescentrum Dierplagen (KAD, Dutch knowledge centre on animal pests), knowledge base; Milieu Centraal; literature study by Wageningen University students for Super Ninja (ACT 2428, 2020), including Aak et al. (2019) and Eder (1940).
