What is the 'Silverfish,' the insect that looks like a sea slater lurking in storm shutters? A thorough explanation of its identity and countermeasures
When cleaning inside or around the house, you might be startled by a small insect moving quickly in the corner of your eye. Many people have likely seen a silver-colored insect scurrying away, especially when opening storm shutters.
If you think, 'It looks like a sea slater' or 'Is that a pill bug?' and look it up, it is highly likely that it is an insect called silverfish.
In this article, we will explain in an easy-to-understand way the identity and habits of the silverfish lurking around storm shutters, as well as the actual damage they cause and effective countermeasures.
Basic Information about Silverfish
Appearance Characteristics
Silverfish are small insects with a body length of about 7 to 10 mm. They are characterized by a silvery-white or gray scaly body surface and a long, flat body shape. They have antennae and three tail filaments, and they move around quickly in a wriggling motion. They were named 'silverfish' (kami-shimi in Japanese, literally 'paper fish') because their appearance resembles a fish.
Where do they live?
Silverfish prefer dark, humid environments.
Behind storm shutters and in gaps in window sashes
Deep inside closets and bookshelves
Under tatami mats
Places where paper, cloth, and cardboard accumulate
Especially in older houses, they tend to settle in structural gaps and places where humidity easily builds up, and the area around storm shutters is a perfect hiding place.
What do they eat?
As their name suggests, silverfish eat paper and things containing starch.
Books and documents
Shoji paper and fusuma (sliding door) paper
Old cardboard
Clothing (especially natural fibers and starchy parts)
In other words, they are troublesome pests that, if left alone, will chew holes in your precious books, photo albums, and seasonal clothing.
Differences from sea slaters and woodlice
Silverfish are often said to 'look like sea slaters,' but they are actually completely different creatures.
Sea slaters: Crustaceans found at the seaside. They are large, 2-3 cm in length, and do not appear in storm shutters.
Woodlice and pill bugs: Terrestrial crustaceans. They have round bodies and short legs. They are often found under fallen leaves.
Silverfish: Small, flat bodies with a silvery luster. They appear in storm shutters and indoors.
Even if they look similar at a glance, if you observe them closely, you will see they are completely different species.
Why silverfish tend to gather in storm shutters
High humidity
The back of storm shutters has poor ventilation and tends to become humid due to night dew and rain. Since silverfish are sensitive to dryness, they prefer such damp environments.Many gaps
Storm shutter rails and shutter boxes have many small gaps, which serve as hiding places to protect them from predators.Food is nearby
If you place cardboard or newspapers near the storm shutters, they become food for the silverfish.
In other words, the structure of the storm shutters themselves has become a 'safe home' for silverfish.
Damage caused by silverfish
Silverfish do not sting or bite humans. However, they quietly spread damage inside the house.
Small holes appear in books and documents
Shoji screens and fusuma sliding doors are eaten
Small bite marks are left on clothing
They are a major enemy, especially for people who collect old books. Valuable materials can sometimes be damaged by them without you noticing.
How to prevent silverfish infestations
1. Remove moisture
Open storm shutters regularly to let air circulate
Place dehumidifiers in closets and bookshelves
Wipe moisture off storm shutter rails
2. Reduce food sources
Do not accumulate cardboard boxes
Dispose of old newspapers and magazines promptly
Store books and albums in airtight cases
3. Seal gaps
Seal gaps in storm shutters and window sashes with caulk
Repair holes in screen doors and shutter boxes
4. Insecticide and extermination
Set up commercially available 'silverfish traps' or adhesive traps
Spray pyrethroid-based insecticide onto storm shutter rails and shutter boxes
Sprinkling silica gel powder (desiccant) into gaps can exterminate silverfish by drawing moisture from their body surfaces
Personal experience: A story about tracking down the identity of the bug hiding in storm shutters
One homeowner was very alarmed, thinking, 'A sea slater is in my house!', after seeing several silver-colored bugs quickly scurry away every morning when opening the storm shutters. However, after having an expert examine them, it turned out they were actually silverfish.
In that house, old cardboard boxes were being stored in the storm shutter box, which provided both moisture and food. Once the cardboard was removed and the shutter rails were cleaned and treated with insecticide, they were hardly seen the following month.
Summary
The small bug that looks like a sea slater often seen behind storm shutters is, in many cases, a 'silverfish'.
They have small, silver-colored bodies and prefer dark, humid environments
They feed on paper and fabric, causing damage to books and clothing
They are harmless to humans, but leaving them unchecked can damage household goods
They can be prevented through moisture control, removing food sources, sealing gaps, and using extermination agents
Silverfish are also a sign that your home's environment is damp. If you see them around your storm shutters, it is a good opportunity to review the ventilation and storage conditions of your entire house. Take thorough measures to protect your precious books and clothing.