Silverfish

Species most commonly found in homesSilverfish (Lepisma saccharina)
SizeUp to 11 mm
LifespanUp to four years
ReproductionUp to 70 eggs, the development takes many months
FoodStarch- and sugar-containing substances
DamageSpoilage of food, wallpaper, books, pictures, starched articles of clothing
ControlDehydration (reducing the humidity or celite), bait stations (insecticide)

Description

The taxonomic group of silverfish (Lepismatidae) belongs to the primitive insects (Zygentoma). They do not possess wings at any stage of their development. They owe their name to their rearward tapering body shape, and the mostly silvery scaling of the older creatures.

Silverfish (Lepisma saccharina)

The most frequent species of silverfish in homes is the Lepisma saccharina. Further details contained in this text refer exclusively to this species. This silverfish grows to a length of up to 11 mm and possesses three cerci, each ca. 3 mm long. The silver scales are mechanoreceptive sensory organs.

Occurrence and Reproduction

Silverfish require a warm and moist environment. They are therefore primarily found in bathrooms. The eggs of the silverfish – an average of 70 are laid at a time- are oval-shaped, white and approx. 1 mm in length. Older eggs take on a brownish colour. At a temperature of 30°C, larvae hatch after approx. 25 days. At a temperature of 20°C the period of development is 40 days. At first, the larvae are white in colour. The silver scales come to the fore after the second shedding of the skin. A further four to five sheddings follow until the animal is fully-grown. Adult animals also frequently shed their skins. Silverfish have a life expectancy of up to four years.

Behaviour

Silverfish avoid daylight and hide themselves in small cracks and other suitable locations during the day. They are extremely negatively phototactic (avoid light). These thin-skinned creatures require a high degree of humidity, where more than 70% relative humidity is optimal. Silverfish are fast movers, but they are not, however, able to climb up vertical walls. They feed on starch- and sugar-containing substances, and can survive without food for up to ten months. During cold periods silverfish are inactive.

Economic Impact

As starch and sugar are contained in a variety of materials, damage may be done to foodstuffs such as pasta, pastries or pulses. But also wallpaper, books, pictures, museum artefacts and starched articles of clothing can suffer damage.

Control Measures

As silverfish require an environment with a high level of humidity, reducing that humidity to under 30% is fatal to these creatures. They also die at temperatures in excess of 35°C. If celite (diatomaceous earth) is spread over the silverfish’s hiding places, crawling over the fine crystals will damage the cuticle (“skin”) of the silverfish, which in turn leads to dehydration. Silverfish can also be combated with bait stations containing an insecticide.

Aeroxon Silverfish Bait Station*

Effective control of silverfish indoors

Silverfish Bait Station*