Silverfish look like something straight out of Star Trek. This little common household invader hides in homes all over. Do they bite? What do they eat? Are they dangerous? Lets look into the facts of the silverfish!

An adult silverfish
silverfish. Insect Lepisma saccharina, Thermobia domestica in normal habitat

History, Families and Distribution

Silverfish belong to the animalia kingdom, under the ‘Insecta’ class and are then further divided into the subclass ‘Apterygota’. A phylum is a taxonomic category that a creature belongs to within a kingdom and ranks before class. The phylum, a silverfish belongs to is known as ‘Arthropoda’ with ‘Hexapoda’ as the subphylum. Silverfish come from the Lepismatidae family under the order ‘Lepismatidae’.  The order zygentoma was called ‘thysanura’ up until the late 20th century (before it was recognized that thysanura was a paraphyletic group). The name of this order was derived from the Greek works ‘zygon’ and ‘entoma’, with the former word meaning ‘bridge’ and the latter ‘insects’ and collectively meaning ‘cut into’ referring to the segmented bodies of the insects belonging to this group. Zygentoma has five subfamilies, the Lepismatidae is one of them, with the other ones being; Nicoletiidae, Lepidotrichidae, Maindroniidae and Protrinemuridae. The scientific name for silverfish is ‘Lepisma saccharina’ which is derived from the name of the genus it comes from, which is, ‘lepisma’. 

silverfish are primitive and ancient creatures that have been around for a long time. In fact, it is believed that silverfish predate even the dinosaurs by 100 million years, which means that they have been around for almost 400 million. They are also categorized as some of the least evolved insects currently.  They are cosmopolitan species, which means that in appropriate habitats, they are found all over the world such as the Americas, Africa, Australia, some parts of the pacific etc. a species is considered to be a ‘cosmopolitan species’ when geographically, they are found in most if not all regions. 

Physical Appearance

silverfish are generally 13 to 25mm long, with a flat, hairless body. These creatures have an exoskeleton that is silvery, shiny and has flexible scales. this type of skin helps give them protections against larger insects, like a spider. Furthermore, their bodies are wide at the head but are tapered at the abdomen. Silverfish move around in a wiggling manner. The structure of their bodies, the way they move and the type of their skin make them resemble a fish, making them stay true to their name. attached to their heads, they have 2 long and slender antennas, however, they are not longer than the body. While on the other side of the body they have 3 appendages. One that continues straight from the edge of the body while the other two separate at an almost 90-degree angle from the middle appendage to either side of the body (left and right). Adult silverfish are grey and silver with a tinge of brown while new hatchlings are pale white in color but gradually put on a greyish hue and a shiny metallic and scaly skin as they grow up. Unlike some other insects in the zygentoma order that are eyeless, these insects have 2 small compound eyes. These creatures share a mutual physical attribute with all the other insects under the subclass ‘Apterygota’ and that is that they are completely wingless. Furthermore, like many other insects, they have many legs. 3 pairs to be specific. 

Commonly Known Types of Silverfish

Some of the most commonly seen and known silverfish include;

  • Common silverfish
  • Four-lined silverfish
  • Gray silverfish
  • firebrat

Common silverfish is a wingless creature that can grow up to 1 to 2 inches. They are nocturnal insects that are active during the night and hide during the day unless disturbed. Their scientific name is lepisma saccharina. they prefer damp, indoor places such as kitchens and bathrooms. This type of silverfish can live for up to eight years. The scientific name for the four-lined silverfish is ‘Ctenolepisma quadriseriata’. They like the common silverfish are also wingless but are a bit longer. On their stomachs, they have four dark lines (hence the name) which makes this type pretty distinguishable. Unlike common silverfish, this type prefers to nest in flowerbed mulch and roof shingles or attics if indoors. Ctenolepisma longicaudata is the scientific name for the gray silverfish. As the name suggests, they are gray in color and are often quite dark and prefer to live in places such as attics. Last but not least, the firebrat silverfish with Thermobia domestica as its scientific name has a long flat and yellowish body. The firebrat gets its name from the fact that you find them only in places that have temperatures above 90 degrees, such as fireplaces, furnaces and insulation. 

Where Can You Find Silverfish?

Silverfish although sometimes do live outdoors are mostly found inside, as they prefer the indoors more. They like to stay in dark damp and humid places such as attics, basements, cabinets, fireplaces, and furnaces as long as they are near food sources. When laying eggs to protect them females lay them in wall crevices or small holes, where it is very unlikely for anyone to find.

Eating Habits

silverfish have destructive eating habits. They like to feed on carbohydrates such as sugar and starch. Common food sources could be:

  • cellulose
  • silk
  • linen
  • paper
  • hair follicle
  • dead insects
  • food crumbs

What Do They Do?

silverfish are nocturnal insects that are active during the night and if not disturbed or threatened stay hidden during the day to avoid daylight. Silverfish can be categorized as social insects since they live in colonies. They feed on anything and everything ranging from clothes to paper to hair to food crumbs, which gives them the reputation of being destructive. Since they have 6 legs, they are pretty quick while running and can easily outrun their predators, however, the fact that running for them is only possible on horizontal surfaces should be noted. They are not good climbers. Silverfish also shed their skin well into adulthood, which is pretty uncommon for an insect. On average a silverfish may shed up to 40 to 60 times in its lifetime.

Reproduction

The mating process among these insects involves a ritual of 3 steps. This process takes about 30 minutes or so.  During the first stage, the male and female silverfish face each other and touch their quivering antennas with one another, step back and then proceed to do it again. This process is repeated a few times. After that, stage two begins, during which the female chases the male while it runs. Lastly, its time for the third stage to take place, which is when the physical process of reproduction actually starts. The male and the female stand side by side, the male then vibrates it’s tail against the female and produces a spermatophore, which in easier words can be called a ‘sperm capsule’ which is covered in gossamer. Through her ovipositor, the female then takes the capsule into her body which results in the fertilization of eggs. A female after reaching adulthood has the ability to lay eggs every day and the number of eggs she can lay in a lifetime goes up to a staggering 100. The female lays eggs in secure places such as wall crevices, away from the threat but close to food. The eggs then take anywhere from 3 to 6 weeks to hatch and after hatching takes another 3- 4 weeks to develop it’s gray color as it is pale white when first hatched.   

Life Span

the life cycle of a silverfish is quite different from most insects. Of course, the process varies from specie to species but generally after hatching it takes the 4 to 6 weeks and numerous molts for the hatchling to enter adulthood and a sexually mature stage. After that, a silverfish can live for 4 to 6 years however, if the conditions such as the environment and the availability of food resources are appropriate, they may even live up to eight years.  The fact that silverfish can live for weeks without food and water also prolongs their life and sets them apart from a lot of other insects.

Are They Dangerous? 

Silverfish are not dangerous creatures. They don’t bite nor do they sting with their appendages.  In fact, they don’t even carry any diseases. However, their existence in a household is considered a nuisance, considering the fact that they eat almost anything. They have a destructive reputation. If they are nesting in your house, it wouldn’t be surprising to find your books, clothes and other household things ate away at. Since they shed a lot, you may even find scales near their nesting areas which for some might be very annoying. Other then that, even if silverfish don’t carry diseases, sometimes people are allergic to them and when they shed and mix up with dust, it could cause a possible allergic reaction. Furthermore, even though silverfish themselves are not dangerous, them being able to reside in your house might be concerning as there may be a different underlying problem. what that means is that silverfish nest in damp and humid places. They need moisture.  And if they are living in your home it could some pipes are leaking, water got in from the outside, or the house in general just has a weak structure which could turn into a huge problem. 

Silverfish and Earwig

Earwigs belong to the animalia kingdom, under the class ‘insecta’ and its respected phylum is known as ‘Arthropoda’. The superorder this creature belongs to is called ‘Exopterygota’ and is further divided into the suborder ‘Dermaptera’. This name Is derived from Greek with it’s first half ‘derma’ meaning skin and the second half ‘ptera’ meaning wings. And the name of this specific creature ‘earwig’ is derived from old English words ‘eare’ and ‘wiga’ meaning ‘ear’ and insect’ respectively. Experts believe that this name was given to them because of their hind wings, which resemble human ears when folded. That and because there have been old tales and cases of earwig beings found in ears. 

Comparison: Silverfish Vs Earwig

  • Difference in families

Silverfish and earwigs belong to the same kingdom, class, and subclass (animalia, insecta and apterygota) however, both belong to different super and suborders. Silverfish to the superorder ‘Lepismatidae’ and suborder ‘Lepismatidae’. Whereas earwig to the superorder ‘Exopterygota’ and suborder ‘Dermaptera’

  • The difference in physical appearance

Silverfish are grey shiny flattened creatures with 3 antennas compared to the dark black-brown earwigs which have 2 pincers. Silverfish are half to an inch long while earwigs are one-fourth to an inch in size.

  • The difference in nesting habits

Both earwigs and silverfish live in moist places, but earwigs prefer darkness and outdoors, while silverfish prefer molds as ideal homes.

  • The difference in eating habits

Silverfish enjoy a starch-rich diet explaining why they feed on paper products and molds, earwigs, on the other hand, eat decaying organic matter.

  • The difference in the reproduction process

The reproduction process of silverfish includes 3 steps; the quivering of antennas, chasing the male and insertion of sperm through the ovipositor to fertilize the eggs. after that eggs are laid (a female silverfish can lay up to 100 eggs in her lifetime and every day after reaching adulthood). After the egg is laid, it takes 3 to 6 weeks to hatch. Earwig reproduction in comparison consists of the male and female living in secluded areas such as crevices, chambers of debris, etc. after they mate, the sperm sometimes stays in the females for a few months before fertilization. In midwinter or early spring, the male then leaves or is chased out from its residence by the female and the female will then lay around 20 to 80 eggs in about 2 days. The eggs when laid are white but turn brownish right before hatching.

  • The difference in life spans

After hatching, it takes 3-4 weeks for the silverfish nymphs to enter adulthood and from there on then, depending on their environment, food and water supply, a silverfish can live up to eight years. Earwigs, on the other hand, have the life expectancy on average of just one year. 

How to Get Rid Of Silverfish (Preventive Measure, Signs, And Effective Way To Get Rid)

These moisture driven insects are attracted to households for one purpose alone, food. It’s always better to be prepared and to prevent disasters like a silverfish infestation beforehand. You can do that by keeping their main motivation to invade your houses at bay. sealed in airtight jars and sturdy bags, to store your food will help you in keeping them away. Another good idea to prevent an infestation is to eliminate favorable conditions such as; moisture and humidity. By doing this, you will provide them with a harsher environment, greatly reducing the chances of an infestation. To do this, the use of dehumidifiers, tightening of pipes, use of sealants and proper drainage and ventilation of rooms and basements is advisable. Silverfish being omnivorous creatures like to feed on organic matter, such as papers, clothes etc, so as an extra precautionary step, In case of an infestation you are advised to keep your valuable paperwork and other attracting food sources in safer places. 

However, sometimes when preventive measures aren’t taken or are taken too late and you think an infestation has already begun and want to be sure of their presence, look for irregular cuts and scrapes on paper indicating a silverfish feeding pattern. Another sign could include looking for silverfish feces. If little, black, grain-like structures that resemble a peppercorn appear in or near possible nesting grounds, it is quite possible that your suspicion about an infestation may be correct. And lastly, Since silverfish shed their skins throughout their lives, these tiny scales are also an indication of their existence. However, one might confuse them with dust, so if you’re suspicious, make sure to look more closely.

Once you’ve determined that there is indeed a silverfish infestation, it’s time to take action. Using basic home remedies like trapping them using special traps available both online and in stores is the easiest way. another silverfish poison is also pretty effective and easily available, however, it’s not recommended if there are children and pets in your house. Another popular approach against silverfish is to use bait. You can leave an irresistible treat for them to take climb over such as a wet newspaper and then once they have taken the bait, you can throw it out. Lastly, the use of essential oils can also prove to be very effective and safe. for example, the oils in dried bay leaves are known to repel these insects so scattering them would be an excellent idea. Cedar oil mixed with water sprayed in suspected infected areas can also drive them away as they despise it. 

However, sometimes if the infestation is too big, and the situation is out of control, with no sign of home remedies working, you are advised to call your local pest control and ask them for the best course of action. 

How to Get Rid of Earwigs?

Earwigs are prehistoric creatures that have roamed the earth for millions of years. However, them roaming around in your garden and your home in significant numbers can and should be a sight of concern. Inside houses, their general appearance and those horrid looking pinchers with a painful sting make them quite scary. However, these six-legged critters are harmless as they aren’t poisonous and carry no disease. In fact, controlled numbers of these insects can be quite useful in gardens but an overpopulation could lead to devastation to vegetation and even ornamental plants, and especially vulnerable seedlings.

Earwigs wander into our homes looking for nutritious snacks like wet paper and smaller insects, and if conditions like humidity and moisture are favorable they tend to stay a bit longer. In gardens however various acts invite earwigs to infest, including overwatering plants, rotting or decaying bark and leaves and even an abundance of tiny insects like aphids. 

To keep these pests under control it’s recommended to use diatomaceous earth which will restrict these insects from reaching the plants. Spreading petroleum jelly on leaves is also a popular method as earwigs tend to avoid it. Alcohol can also be used as an insecticide to kill off pests instantly. Sprinkling borax near woodpiles is also a way to keep them busy however keep kids and pets away after doing so. In houses however the best remedy is to reduce moisture levels by using dehumidifiers, ventilators and a proper inspection of pipes and drainage to ensure there are no leaks. Do make sure there are no wet newspapers lying about the house. These measures alone will keep your house earwig free.

Dusty Showers has been in the urban nuisance wildlife and pest control field since 1993. Taught by Garon Fyffe, a pioneer in humane nuisance wildlife management, Dusty has a passion for finding humane solutions to human & wildlife conflicts. Dusty was the only individual invited by the Florida Fish & Wildlife Commission in the lat 1990's to help write legislation for legal protection of Florida bats. With an instinct for solving wildlife, Dusty found pest control to be an easy "add-on interest". Dusty started his first business "Animal Instincts Wildlife & Pest Management" in the Tampa Bay, Florida area in 1995. Eventually selling Animal Instincts in 2002, Dusty went on to start Creepy Creatures Termite and Pest Control in 2009, which he still owns and operates today in Palm Harbor, Florida.