If you ever had a moth in your home then you probably saw fine dust coming off of its wings. Especially when you touched or smushed a moth you will have seen this fine dust. But what is this dust and what does the moth need it for?
As a whole, the wings of a moth aren´t dusty, they are covered with fine scales that look like dust to us. The moth uses these scales for several things like insulation, a defense against spiders, camouflage during the day, and flying.
The reason why the scales come off so easily is because the moth uses its scales to get out of sticky spider webs. The scales come off at the slightest touch causing the spider web to get covered in them reducing the stickiness of the web.
What is the Fine Dust Coming off of the Moths Wings?
As I already mentioned before, the fine dust isn´t actually dust but very fine scales that are microscopic in size.
You can see them in this close-up picture of a moth’s wing. Notice how the pattern seems somewhat pixelated? That’s where the different colored scales lay above each other.
The moth has a lot of these scales and it produces way more than it actually needs because it uses them for several things including as a defense mechanism.
That is also why the scales come off right when you touch the moth.
What are the Scales for on a Moths Wing?
The scales on a moth’s wings are used and needed for several important things. But not every single use is known and some of these use cases are pure speculation based on observation.
The scales on the wings of the moth are differently colored and give the moths wings their appearance.
The moth is nocturnal and therefore it usually sleeps during the day. But it needs some sort of camouflage so that it is not easily spotted by predators during the day.
That´s why moths are usually white, brown, or black in color. They sleep on trees or in bushes during the day.
The scales help them to create their camouflaging colors and patterns. It is believed that some moths can change their colors and even their patterns depending on where they live.
Some moth species can appear white when they live in areas with a lot of birch trees (birch trees have white bark). And the same species can also appear brown in other regions with little birch tree population.
Defense Against Spiders
It is also believed that some moth species use their scales as a defense against spiders.
When a moth is caught in a spider web the scales fall off of the moth’s wings and make it so that the spider web is no longer sticky enough to hold the moth in place.
The moth will then move around until it can free itself and escape.
The tiny scales are very effective insulation against the cold at the night.
The scales stack on top of each other creating insulation that will keep the moth warm enough to fly.
Lisa is one of the two founders of Animal-Knowledge. She has been very interested in animals and insects from a very young age and has owned different kinds of pets such as snails, ants, fish, turtles, mice, rats, hamsters, rabbits, a dog, … you get the idea 🙂