Tiny Grey Bugs on Window Sill – What Are They?

Have you noticed those strange dust moving on its own on your window sills during summer? They’re no dust. They’re teeny, weeny little bugs. Tiny grey bugs on the window sill – what are they?

Those tiny bugs could be fungus gnats if plants are near your window. You can be sure that they are fungus gnats if their colors are light grey and if they can fly. Other tiny bugs could gather on your window sill. They can include booklice, clover mites, and many more.

If you notice that the ‘dust’ is moving on its own, these things are alive. These tiny bugs can get inside your home, not just on your window sills. When that happens, they can bring diseases with them. Be on the lookout for these pests when your neighbor has planted a new lawn, or there’s a heavy growth of grass close to your walls.

Read on to learn more about these tiny grey bugs that wander on your window sill and what you can do about them.

Tiny Grey Bugs on Window Sill

tiny grey bugs on window sill
Fungus Gnat

You will notice the appearance of tiny grey bugs on your window sill if there are plants nearby. Most likely, they will be fungus gnats if their colors are light grey and they can fly.

But there are other kinds of small grey bugs on the window sill. They can include booklice, clover mites, and many other annoying teeny creatures.

Expect these little pests to wander on your window sills if your neighbor has recently established a new lawn or if there is heavy growth of grass near your wall foundation. They are coming from your window because of holes and cracks.

So, if your windows are old and their frames have seen many years, these little pests will use the holes and cracks in them to get inside your home, annoy you, and perhaps cause you to become sick.

You must block their entries by checking all the holes, cracks, crevices, and openings in your windows. If their entry is not checked, these tiny grey bugs can infest your home and create many nuisances, including sicknesses.

Similar to silverfish, some bugs can slither across your kitchen or bathroom. You need to know the small grey bugs that can invade your home through your windows. And you also need to know how to prevent them from infesting your home.

The rest of this article will dwell on these two essential elements of our topic today.

What Are These Tiny Grey Bugs on Window Sill?

1. Clover Mites

tiny gray bugs on window sill

Leaves a Reddish Stain When Squashed

Clover mites are one of the tiny grey bugs you commonly see in window sills. You will know they are clover mites if they leave reddish stains when they are squashed.


While they are common, they are also harmless to us. However, they are a nuisance because they can infest not just windows but also sliding doors and basement window wells.

Eliminate Clover Mites by Using a Vacuum

You can eliminate clover mites by vacuuming them because they’re so minuscule. But then you must empty the vacuum pouch immediately, or they will infest other parts of your house. They are pretty active during spring and fall, so watch out for them during these seasons.

Use Perimeter Treatments

You can also prevent them from entering your premises by using what is called perimeter treatments. This can be in the form of a physical barrier or a chemical barrier.

A physical barrier can be a strip of stone free of grasses before the walls of your house. If you want a chemical barrier, you can use insecticides or soaps that you can apply to your windows and window frames.

2. Springtails

small grey bugs in windowsill

Arthropods That Jump and Feed on Rotting Leaf Litter

These tiny creatures are arthropods that jump and feed on rotting leaf litter. It makes them threatening that they have thousands of varieties – 6,000 of them. They will swarm your windows (and possibly your home) if you have plenty of mulch around your house. 

Rid the Inside and Outside of Your Home of Rotting Materials

While they are also harmless to us, they can still be a source of nuisance and diseases. To get rid of these pests, ensure there are no rotting materials, grasses, wood, and the like around your house.

Check for Any Water Damage Around Your House

Also, check for any water damage around your house. Water can make waste materials decay faster, which will then attracts springtails. Fix the cause of the water damage, and you will fix your problem with these little creatures. You may need the help of a pest control service to do this.

3. Booklice

very small grey bugs on window sill

Feed on Fungi and Mold

Booklice are one of the most common tiny grey bugs you will see wandering on your window sills. These bugs like to feed on fungi and mold. They grow and multiply in damp and humid environments. That’s why you will commonly see them on windows and window sills.

Hide in Books

They also love hiding in books, earning their ‘booklice’ name. Since mold and fungus are their primary food source, you can get rid of them by getting rid of these organisms.

Reduce the House’s Humidity

Perhaps you are living in a high humid area. You can reduce the humidity in your house by pumping up the heat or using a dehumidifier.

Can Contaminate Food

While booklice are commonly found in windows, window sills, and books, that does not mean they will not invade any part of your home once they are allowed entry. These small pests can also infest your pantry, where they can eat and contaminate your grains and other food.

So, reduce the humidity in your place once you see a throng of booklice outside your windows.

4. Biscuit Beetles

what are the tiny bugs in my window sill

Drugstore Beetles

Another type of tiny grey bug that can assemble on your window sills is the biscuit beetle. These small insects are also called drugstore beetles. They are not related to pantry moths, but they share certain characteristics that can irritate us. These insects love to raid pantries in their search for food.

Attracted to Lights

Biscuit beetles are attracted to lights. They attach themselves to your windows when you turn on your house lights. If there are open cracks on the window frames, they will readily use these openings to invade your home.

Use Vacuum

You can eliminate them by vacuuming them thoroughly wherever you suspect they have infested your home. Empty the vacuum where they can’t get back inside your home.

You should also thoroughly clean your house because they can hide in any small nook and crevice inside your house. If you leave them alone, they will infect your home again and again.

Don’t wait until the situation gets serious and you are forced to ask the help of a professional pest removal service to get rid of them.

Again, what are the tiny grey bugs on my windowsill? The tiny grey bugs on your window sill might be clover mites. If there’s a newly established lawn near your window or heavy growth of plants, then it’s likely that the tiny moving specks are clover mites.

5. Silverfish

how to get rid of tiny bugs on window sill

Has Iridescent Grey Color

You can include the silverfish in these tiny bugs that can populate your window sills. Silverfishes are very small creatures with bodies that have iridescent grey colors. Adult silverfishes are less than an inch long and slither smoothly as they move as if swimming.

Leave Behind Iridescent Scales on Their Tracks

When actively moving, they leave behind iridescent scales on their tracks. So, if you see their small scales, they have infested your home, even if you don’t see them. These tiny creatures are nocturnal and are attracted to dark places. That’s why you will hardly see them during the day.

Thrive in Damp Places

Like other grey bugs, silverfishes also love damp places. So, you can see their tracks in sinks, drains, and bathrooms. They love to eat hair, leather, paper, cloth, wallpaper, and glue. For this reason, many have attributed this kind of damage to moth infestation.

Spread Borax in Places Where You Suspect Silverfishes Stay

The quickest way you can get rid of silverfish is by using borax. Spread a thin layer of this powdery substance in places where you suspect silverfish are staying. It can be at the back of a kitchen cabinet, inside closets, along baseboards, or beneath your washing machine or dishwasher.

6. Pill Bugs

how to get rid of tiny black bugs on window sill

Also Called Roly-polies

Another small grey bug that you can see on your window sill is the pill bug. These tiny creatures are also called roly-polies.

Not Insects

They are not insects but isopods, a type of arthropod, a terrestrial crustacean. These isopods are called roly-polies because they tend to roll into a ball when threatened.

Nocturnal Creatures

Pill bugs are also nocturnal creatures. They cannot retain moisture in their bodies, so they prefer to live in constantly wet and humid places. These tiny bugs like to live in dark and damp environments such as basements, bathrooms, sinks, and garbage disposals.

Enter the House Through Cracks

You can accidentally bring roly-polies inside your house when you have dirt on your shoes while gardening. They can also find their way inside your house through cracks in your doors, gutters, and spouts.

Sprinkle Diatomaceous Earth on Areas with Pill Bugs

You can get pillbugs out of your house by using diatomaceous earth. DE is available in any house improvement store. Sprinkle this substance on areas where you suspect pill bugs are staying.

If they eat this DE, it will absorb their body moisture. As their body fluids dry out, they will die. DE will also be a bug repellant because pill bugs dislike crawling on them.

7. Fungus Gnats

window sill bugs

Small Flies That Live on Soil

You are already acquainted with fungus gnats which I mentioned at the beginning of this article. But what are they? They are small flies that like to live on soil, potting mix, and other media containers that contain decomposing organic materials.

Larvae Thrive on Organic Matter in Soil and Fungi

The larvae of these tiny creatures thrive on organic matter in soil and fungi. They also live on plant roots. So, they can be a problem in potted plants, nurseries, interior plant scapes, and greenhouses.

Harmless to Humans

These insects are harmless to humans. They don’t bite, and they can’t spread diseases. However, they can pose a problem with your houseplants. When they have invaded your home, their larvae will decimate the thin roots of your plants.

Deal with Fungus Gnats Using 3% Hydrogen Peroxide

One of the best methods of dealing with fungus gnats is hydrogen peroxide. You can use the regular 3% topical formula. Mix this chemical with water to get rid of fungus gnats. The concentration of the mixture should be four parts water and one part hydrogen peroxide.

Pour this mixture where you suspect these gnats are attacking your plants. Concentrate at the root zone of the plants until the substance leaks out from the pot’s base. The larvae of fungus gnats will be killed when they come in contact with this mixture.

Frequently Asked Questions – What Are the Tiny Bugs Near Window?

There are many types of bugs that you can see outside your window sills. When you see them there, it is natural for you to get disturbed since they are poised to invade your home.

Naturally, you will have questions about them that you want answered. Perhaps, you will find the answers to your questions below:

What Are Those Tiny Grey Bugs Lingering on My Window Sill?

If there are plants near your window or thick grass growth near your house, the tiny bugs you see on your window sill are probably fungus gnats. Your guess could be right if the body colors of the bugs are light grey and if they can fly.

While they don’t bite and are harmless to humans, they can still destroy your potted plants. If you have an indoor nursery, they can invade it and damage the plants you are cultivating there. They love to eat the roots of plants.

So, this is where you can find their larvae. Eradicating their larvae will stop the infestation of fungus gnats in your home.

What Are Other Kinds of Grey Bugs on My Window Sill?

You may see several other small grey bugs on your window sills. They can include:

  • Booklice
  • Springtails
  • Clover mites
  • Silverfish
  • Roly polies
  • Biscuit beetle

Why Do These Tiny Grey Bugs Congregate on My Window Sill?

They are attaching themselves to your window sill because there is probably something there that they can eat. Or perhaps they are attracted to your window sill because of its wet and humid state.

These tiny creatures live and thrive in places where there’s moisture and high humidity. Unfortunately, window sills are constantly exposed to moisture in the surroundings, especially if you live in high humid regions of the country.

How Can I Get Rid of These Tiny Grey Bugs on My Window Sills?

If you know that most of these small grey bags are attracted to damp places, like your window sill, then the basic solution is to reduce the dampness and wetness of the place. But if it’s always raining outside, you certainly can’t just do that.

You can seal or close all the openings and cracks on your windows and window frames that these bugs can use to get inside your home. The easy solution is to use a good caulking material to close those gaps, cracks, and openings fully.

Another thing you can do is remove plant growth near your windows and your walls. These tiny creatures use those plants’ branches to get to your windows. If no plants are near your windows and walls, these creatures will have no bridge to cross your windows.

You can also use pesticides to deter these pesky creatures from attaching themselves to your window sills and eventually getting inside your home. Borax powder is one substance you can use to prevent them. They don’t like the smell of borax, and they don’t like crawling on this powdery substance.

In Closing: What Are Those Grey Bugs on My Window Sill?

Those tiny grey bugs on your window sill could be fungus gnats if there are plants near your windows. If they are light grey and they can fly, they are most surely fungus gnats.

However, other tiny bugs can also gather themselves on your window sill. Most often, they will be booklice, clover mites, and other tiny bugs.

Most of these tiny grey bugs are harmless to us. But they are a nuisance once their numbers begin to increase. They can disrupt your normal activities, so you must remove them from your house.

If you follow these methods I have discussed in this article about how you can get rid of them, they will be discouraged from returning.

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