When dealing with insects, it’s always important to know exactly what type of problem you have on your hands. Solutions and products that work on one type of insect are often ineffective on others, even if they are a part of the same overall family group.
Additionally, lookalike insects can often have drastically different (or no) effects on your home, property, and health. The same goes for silverfish and insects that look like silverfish as well.
Silverfish grow without changing their body structure (i.e. without metamorphosing). They reproduce relatively slowly and live longer than most other insects. While they have a relatively unique body structure, they can still be mistaken for some other insects. That’s why, in this article, we’ll cover exactly what silverfish look like and go over some of the insects that look similar to silverfish.
What do silverfish look like?
They have two long antennae on their heads as well as three slender bristles that trail out behind them. Their tapered, carrot-like bodies are covered with shiny, silvery scales. It’s this coloring, in combination with their scales, that has earned them their common name: silverfish.
Silverfish are wingless but quite fast-footed. Adult silverfish can range from 0.4 in. (1 cm) up to 0.75 in. (2 cm) in length. Young silverfish nymphs are small, pale, fat, and lack scales. They’ll go through several molt stages to reach adulthood, continuing to molt regularly throughout their lives. After the fourth molting (about 12 days after they hatch), they’ll grow scales and start to look more like adults. Silverfish eggs themselves are about 0.04 in. (0.1 cm) long.
Silverfish prefer warm, shady, and moist environments with bountiful food nearby. They will travel long distances for food if need be, though. They are also strictly nocturnal, which is why we rarely see them even when they’ve already settled in our homes.
Silverfish Lookalikes: The Most Common Insects Mistaken for Silverfish
As unique as silverfish are, there are still silverfish lookalikes out there. These are often mistaken for their silver-colored cousins. The most common bugs that look like silverfish are firebrats, bristletails, earwigs, centipedes, and woodlice. So, if you want to be certain of what you’re dealing with, here’s a quick breakdown of all the common bugs that resemble silverfish.
Firebrats, or Thermobia domestica, are members of the same insect order as silverfish: Zygentoma. As a result, they’re quite similar to silverfish. They are also flattened, wingless insects that are fast on their feet. Firebrats share similar mating and feeding habits and are also nocturnal.
In terms of their appearance, firebrats are darker in color than silverfish and are brown rather than silver. You will find them in drier habitats. They prefer warmer temperatures than their cousins, so they are often found near furnaces or boilers.
Bristletail is the common name for insects of the order Archaeognatha (or Microcoryphia). Zygentoma, which contains both silverfish and firebrats, is the sister order to Archaeognatha. One of the most common silverfish lookalikes in this order is the jumping bristletail.
Like silverfish, jumping bristletails lack wings and have scales, thin bristles, and long antennae. They are round (rather than flat), gray (rather than silver), and vary in size (from 0.2–0.8 in./5–20 mm). Most bristletails, including the jumping bristletails, are outdoor insects. This means that they will rarely come close to your home or property as there’s nothing of interest for them there.
Unlike silverfish, bristletails can jump as far as 4 in. (10 cm) when disturbed. So, if you scare a bug that you think might be a silverfish and it jumps instead of scurrying away, it’s probably a bristletail.
Even though it is a bit less silverfish-like, an earwig can also be mistaken for a silverfish by the untrained eye. It’s a very different insect, though. Instead of three distinctive bristles trailing behind them, earwigs have two menacing-looking pincers. They’re also primarily dark brown with reddish heads and pale legs. Their most significant commonality with silverfish is that they are both about 0.5 in. (1.2 cm) long.
Earwigs are mostly found outdoors but sometimes venture inside. Even though they may look unpleasant, they’re harmless to humans. You may have heard someone say that earwigs crawl into people’s ears while they sleep, but this is simply not true.
Earwigs feed on live and dead plants in your garden and may sometimes feed on live or dead insects. They will sometimes enter homes in the summer months.
Like the earwig, centipedes have a lot of physical differences when compared to silverfish. You’ll also usually see them from far away. At a greater distance, it’s easier to mistake them for silverfish. One complicating factor is that both silverfish and a lot of centipedes are rather quick on their feet and hide when you try to approach them.
Still, from up close, centipedes are quite easy to tell from silverfish since they have at least 30 legs, if not more. It’s also worth mentioning that centipedes actually like to eat pests such as silverfish, roaches, and ants.
A woodlouse (sometimes booklice), can be mistaken for silverfish thanks to the same grey coloring that some species have. They do have a different body shape, so when compared side by side, you can clearly tell which is which.
A lot of insects can be mistaken for silverfish from afar. But, these ancient insects do have many distinctive characteristics that make them stand out when viewed up close. Only firebrats and jumping bristletails can really be mistaken for silverfish. But, if you examine them carefully, the common types of indoor silverfish are easy to identify.