March 25th, 2021 by Sarah Miles

Looking at them objectively, there is a lot to admire about silverfish: they have been in existence for 400 million years (yes, really) and were designed so effectively for survival from the start that they’ve hardly had to evolve at all. In fact, they can even live for up to a year without any food. What is less impressive is the damage they do to your home.

Like many of us, they are suckers for carbohydrates but rather than reaching for the pasta or chips, their diet of choice is anything starchy - including wool, paper, cotton, carpets, sugar, and adhesives. This is where the issue is. Unlike some other household pests, they don’t bite or carry diseases but it’s still important to deal with them if you suspect you have an infestation as they can inflict incredible damage with their feeding habits.

There are 5 key things to look out for if you think you may have a silverfish infestation:

1. Seeing actual silverfish

It may be stating the obvious but one pretty clear sign is actually seeing them. However, this is very unlikely! They are nocturnal, so they’re most active when we’re in bed. Even if you’re a night owl, silverfish are extremely quick and will hide away at the first sign of trouble, so they can be difficult to spot. They prefer damp, dark locations so be vigilant in bathrooms, kitchens, and behind or underneath furniture. That’s why it’s important to look out for the other signs as well. They are small (up to around 2cm long) and a grey/silver colour. They’re insects rather than fish (obviously!), but they get their name from the way they wriggle when they move which is reminiscent of the way a fish swims.

2. Damage to Fabric, Carpets, and More

Silverfish aren’t predatory, and they don’t bite or harm people or animals in any way. As we mentioned above, they will eat almost anything that contains starch. Common targets include paper and fabrics, which means they’ll often target books (especially old books). They’ll also chew through natural fibres like woollen jumpers or carpets, as well as cardboard boxes, plaster, wallpaper, and more. Seeing unexplained, gradually-worsening damage to any of these things appear warrants further investigation – it could be silverfish.

3. Droppings

Like all living creatures, silverfish produce waste. Their droppings can be quite distinctive, so this is often the best way to identify them. They resemble small, black specks of pepper and will usually be found in the kinds of areas they like to live (cupboards, cellars, and anywhere that’s cool and dark. Keep an eye out for them and if you see anything like this, give it a good examination (however unpleasant that thought might be) as they can be dismissed as dust or dirt.

4. Shed skin

Silverfish shed their skins throughout their life cycle, even as adults. They look like translucent little specks of plastic and can often be found sticking to walls or other surfaces.

5. Yellow Stains

Their moulting can also leave behind yellowish stains or dust. You can particularly look out for this on the things that they feed on, such as books and papers. Check around bookcases and wallpapered areas.

What to do if you think you have a silverfish infestation

If you have seen one or more of the signs above but you’re still not sure whether you have them or what the scale of the problem might be, there is a way of checking. A flushing agent will do exactly as the name suggests: it is an insecticide that has a delayed action. It flushes insects out of hiding first before killing them. Simply spray it in the areas you have spotted signs of them, and into any cracks and crevices. This will also alert you to the scale of the problem.

Of course, as we have established, they are very hardy and built for survival, so you need a belt and braces approach to really make sure you’ve got them. A combination of dusting powder, surface spray, and smoke bombs should allow you to cover all bases. As with many household pests, retreatment is highly recommended after a few days to ensure you eradicated the entire infestation and prevent them from repopulating.