Silverfish

What are Silverfish and how to get rid of them

Silverfish have been around for millions of years and have been found in fossil records as early as the first land-living animals. Silverfish have survived for such a long time because they are known to survive in a variety of very tough environments. Silverfish are best known for their vast destruction of various household items such as books, photographs, artwork, clothing and accessories. Some people may be allergic to the faeces and cast skins (moults) of Silverfish, which may trigger conditions such as asthma.

Although Silverfish are not fast or prolific breeders, they do live for a long time (up to six years!). If left untreated, infestations can reach plague proportions. To avoid damage to property and prevent major infestations, it’s important to control, prevent and monitor for Silverfish in the home.

Description:

Silverfish are heavily segmented and soft-bodied insects, covered in fish-like scales. Depending on the age and species, they are between 2 - 18 mm in length, varying in colours of silver, gold, bronze and brown. The body shape is flattened from top to bottom; and when viewed from above, the body is wide at the head tapering to a pointed rear (abdomen). Often around the perimeter of the body are short fine hairs.

The head is small with two very small compound eyes on either side of the head, however, some species are eyeless. At the front of the head are a pair of very long and straight antennae, greater than half the length of the body. At the front and underside of the head are chewing mouthparts.

Behind the head, on the underside and middle section of the body (thorax), are three pairs of outward facing legs. Silverfish are wingless.

Along the underside and rear section of the body are a series of appendages to help with locomotion and movement. At the tip of the abdomen are three appendages.  The central appendage points directly outwards, while the other two are at right angles to either side of the central appendage.

Behaviour:

Silverfish are fast runners; they can also jump and hop. When disturbed, silverfish either sit very still or swiftly scurry away. Silverfish also have an interesting and elaborate mating ritual.

Lifecycle:

After moulting and mating, adult females lay eggs in clutches of 7- 12 eggs, laying up 60 eggs at a time. In one lifetime, a female lays approximately 100 eggs. Eggs generally hatch within 20 days, however in sub-optimal conditions, they can take up to 40 days. Eggs hatch into juveniles (nymphs) which are similar in appearance to adults, only smaller and lighter in colour. Juveniles grow through 6 - 7 growth phases, shedding skin at each phase. Juveniles take 3 months to 3 years to reach full maturity. Silverfish can live for up to 6 years and continue to moult throughout their lifetime.

Habitat:

Silverfish are attracted to materials containing starch, sugar and protein. They also feed on dust, debris, dead insects, dead skin cells, algae, lichen and fungi. Silverfish can survive for many months without food.

Silverfish prefer dark, warm, humid and undisturbed places. They are most active during the warmer months at night and hide throughout the day.

In outdoor environments, Silverfish can be found in bird and ant nests; and underneath stones, leaves and other debris such as piles of timber.

While in the home, Silverfish are often found in:

• bathroom
• laundry
• basement
• ceiling voids and crawl spaces
• bookcases
• cupboards and linen presses
• window frames
• door frames
• behind skirting boards
• along the fringes of carpet
• underneath, in and around soft furnishings
• near pipes

Silverfish hide in the crevices, seams and junctions of:

• Animal fibres such as wool and silk
• Plant fibres such as some timber, cotton and rayon
• Natural and synthetic fibre blends
• Human and animal foodstuffs

Silverfish feed on various household products and items such as:

• Cereals and grains found in foods such as flour, pasta, pet food, vegetables and dried meat
• Clothing, bags and accessories
• Paper, cardboard, glues and pastes such as the paper and bindings of books, cardboard boxes, photographs, artwork, and wallpaper
• Building materials such as timber, plaster and wall-board, masonry and freshly laid concrete
• Musical instruments, especially the pads in woodwind instruments and felt found in pianos

Best treatment for Silverfish

As Silverfish are highly mobile insects, it is important to treat all areas of the home simultaneously. This will prevent Silverfish moving from one area to the next and starting a new infestation. Once the home has been adequately treated, repeat the same protocol within a few weeks of initial treatment. Continue to follow preventative practices, control measures and monitor for further signs of infestation.

To control Silverfish in and around the home, spray Blitzem! IndoorOutdoor Barrier Spray Ready to Use. These products kill Silverfish on contact and provide a barrier of control for up to 2 - 3 months. Spray all surfaces within wardrobes and cupboards, do not apply to clothing or bed linen.

For delicate fabric items and precious papery items such as books and photographs, take the item outside and brush off and squash any eggs, nymphs or adults that may still be on the item. Place the item into a plastic sealable bag, then seal well to avoid too much moisture getting into the bag. Place item in the fridge for at least three days to kill off any Silverfish. Please note, freezing may cause further damage to the item due to condensation.

For more durable fabric items, place into the washing machine and wash using hot water, then either place in the dryer on the hottest setting for more than half an hour; or hang on the line on a dry, hot and sunny day.

Vacuum and/or steam clean fabric furniture and carpets to kill Silverfish and to reduce dirt and grime build-up.

Hygienically clean the interior of the home.

Symptoms of Silverfish damage

Typical damage of Silverfish to household items include: irregular chewed holes and chewed trails from feeding on papery and fabric items. Damage can be confused with Carpet Beetle and Clothes Moths. Snails damage to papery items is also similar, however snail damage is often accompanied by silvery trails and long skinny poos.

Further evidence of Silverfish infestation:

• Living or dead juveniles and adult Silverfish. Silverfish hide during the day and will generally be found in dark, warm, humid and undisturbed places.
• Faeces are small, black and granular looking, mostly found on or near a food source.
• Eggs are oval, cream-coloured and small, generally 0.8 mm in length. Often found in the crevices, seams and junctions of hard surfaces and fabric items. 

How to prevent Silverfish appearing

Prevent Silverfish from entering the home:

• Check books, cardboard boxes and other papery material prior to bringing into the home.
• Avoid purchasing second-hand furniture, clothing, bags and accessories, otherwise thoroughly inspect for signs of Silverfish prior to bringing into the home.
• Check building materials prior to bringing into the home. If a Silverfish has been seen, rinse off materials with water and squash Silverfish.
• Reduce entry points to a building: repair holes, cracks and gaps in walls, skirting boards, windows and doors.
• Ensure flyscreens are fitted and maintained. If possible, cover vents with a fine mesh.
• Install a door seal or door snake to the bottom of entrance doors.

Reduce the environment favourable to Silverfish:

• During times of high humidity, turn on the air conditioner, fan or heater to help reduce humidity.
• Use moisture absorbers in drawers, cupboards and other enclosed places.
• Keep blinds and curtains open during the day to help keep rooms bright.

Keep the home hygienically clean:

• Regularly vacuum and keep clean: cushions, soft furnishings, cupboards, bookcases, along skirting boards and edge of carpet etc.
• Vacuum and/or steam clean fabric furniture and carpets to kill Silverfish and to reduce dirt and grime build-up.
• Ensure any food crumbs, dirt, dust, dead insects and bird nests have been removed and cleaned as soon as they have been noticed.
• Avoid clutter, especially storing or discarding unutilised paper items.

Exclude Silverfish from vulnerable items:

• Where possible, keep products or items made of natural plant/animal fibres or synthetic blends in plastic sealed containers. For unused fabric items, use vacuum sealed bags.
• Keep all human and pet food in plastic sealed containers.