Pest Lexicon – Green Guardia

Silverfish: Identifying causes & reducing them naturally for the long term

Silverfish are nocturnal, silvery-shining insects that appear primarily in damp rooms such as bathrooms, kitchens, or basements. In most cases, they are not a "hygiene problem," but rather an indication of excessive humidity. Here, you will learn how to identify silverfish and which measures are truly effective in the long term.

ⓘLepisma saccharina · Silverfish #Bathroom · Humidity · nocturnal

What are silverfish?

Silverfish (Lepisma saccharina) belong to the Zygentoma order and are primitive, wingless insects. They love warm, damp areas and hide during the day in cracks, joints, and under baseboards. Silverfish feed on starch- and sugar-containing residues, dead skin cells, and wallpaper paste/glue – which is why they are often found in bathrooms and kitchens.

nocturnal moisture-loving cracks & joints

Important: A large number of silverfish indicates persistently high humidity. If you also notice a musty odor, damp patches, or mold: it is essential to determine the source of the moisture.

How to identify silverfish

silvery-shining, elongated creatures (usually 1–1.5 cm)
3 "tail filaments" at the rear end
scurry away quickly when exposed to light
sightings primarily at night or when turning on the light
frequently found in bathrooms, kitchens, basements, laundry rooms

Green Guardia Tip: Place a sticky trap in the bathroom/kitchen at night. This way, you can quickly see whether it really is silverfish – and how severe the infestation is.

Why do silverfish appear?

excessive air humidity (most common reason)
warm rooms + poor ventilation
many hiding places (joints, baseboards, silicone edges)
food availability: skin cells, dust, glue, crumbs

What to do about silverfish? (natural & sensible)

1. Reduce humidity (the most important lever)

ventilate regularly by opening windows wide (especially after showering/cooking)
check for moisture sources (leaky joints, leaks, condensation)
do not dry laundry in poorly ventilated rooms
use a dehumidifier if necessary

2. Reduce hiding places

seal joints and cracks (silicone, acrylic – depending on the area)
check baseboards, pipe penetrations, corners
vacuum regularly, especially along edges

3. Monitoring & reduction

place sticky traps along their paths (behind the toilet, under the sink, kitchen plinths)
remove crumbs/dust (reduce food sources)

Note on beneficial insects: There are no common, practical beneficial insect solutions for silverfish in the household. Sustainable results are primarily achieved by: lowering humidity + sealing cracks + traps.

Silverfish FAQ

Are silverfish dangerous?

Generally, no. They do not usually transmit diseases. However, many of them are an indication of excessive humidity – and that should be taken seriously.

Why do I only see them at night?

Silverfish are photosensitive and nocturnal. During the day, they remain hidden in joints and cracks.

How do I distinguish silverfish from firebrats?

Firebrats are often slightly larger, appear "hairier"/duller, and tend to occur in drier areas (living rooms), where they can cause more damage to paper/glue.

What is the best prevention?

Keep air humidity low, ventilate well, seal joints, and keep everything clean – especially in the bathroom and kitchen.