Silverfish and the Firebrat

The silverfish and the firebrat are very common household pests.

How to spot them

They are long, slim, scaly, segmented, wingless insects, with a pair of long fine antennae at the front and three tail-like appendages at the rear.

Silverfish may grow to about 12mm in length but the firebrat tends to be larger (14mm) with much longer antennae. The silverfish, as its name implies, is silvery and glistening in appearance whilst the firebrat is greyish with dark, irregular markings.

Habitat

Silverfish are found in fairly moist areas: kitchens, larders and mainly in bathrooms and basements. They can also be found in books and paper, slightly damp cupboards, behind skirtings and loose wallpaper.

The firebrat needs much higher temperatures, ideally between 32ºC and 48ºC. It is often found in bakeries and near ovens and hot pipes.
Both the silverfish and firebrat are nocturnal. They move very rapidly when disturbed and just turning on a light can make them run for cover.

Food

The silverfish feeds mainly on small food particles and the paste on the back of wallpaper that has become detached. It attacks gums and glues of bookbinding, feeds on fragments of dead insects and may also eat textiles such as cotton and linen. The firebrat feeds mainly on food debris.

Life cycle

The female silverfish is believed to lay about 100 eggs, either singly or in groups, usually in crevices and cracks and not glued to the surface on which they are laid. They are small and white when first laid but soon turn brownish and are difficult to find. The time they take to hatch varies from two to eight weeks, depending on the temperature and humidity of the breeding site. Newly hatched insects are about 2mm long and resemble the adults in appearance. The time they take to reach maturity may vary from a few months to over a year, depending on the temperature and humidity of their surroundings.

The life cycle of the firebrat is similar to that of the silverfish but it lays a greater number of eggs.

Control

When only a few silverfish are seen it is not necessary to take any action other than checking for damp.
If large numbers of these insects trouble you they are easily controlled with normal insecticidal spray or dust which can be bought from most hardware stores. Look for the products that are specifically designed to deal with crawling insects.

Dampness

The presence of silver fish is an indication of damp conditions. This may be a warning that repairs are needed. Look at the floor, walls and ceiling for signs of staining due to dampness. Check that all the water pipes, gutters and damp proof courses are intact.

Another common problem is condensation sometimes caused by drying washing indoors (especially by an unventilated tumble drier) or by cooking. Whenever creating steam you should try to keep the internal doors closed and the window open. Bathrooms and kitchens should also have permanent ventilation to the outside - an air-brick or trickle vent on the window.

Prolonged problems with damp can lead to structural damage, dry rot and other serious effects. Seek help from a reputable builder or surveyor if you are unable to repair the damage yourself.