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Black Dots on Your Window Sill? (What They Are and How to Get Rid of Them)

Black Dots on Your Window Sill? (What They Are and How to Get Rid of Them)

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Just as “eyes are the windows to the soul,” your windows offer guests and passersby a glimpse into your home’s interior — and, thus, the soul of your homemaking ethos. First impressions can be hugely important, and you won’t get a second chance at them, so what should you do if you find your windows have been defaced by an outbreak of foul black dots all over the windowsill?

What can you do? Windows mark a transition point between your interior and exterior décor, meaning the unsightly blot of these dots mar both at once.

To have any hope of rescuing your décor, therefore, you’ll need to first diagnose the root of the problem. The two most common sources of black dots on a windowsill are bug droppings (ugh) or black mold (also ugh).

With that in mind, let’s take a closer look at both of those issues, how they occur, and what you can do about them.

Identifying Bug Droppings

You can determine where black dots are coming from on window sill by termite damage

The easiest way to determine if the black dots in question are bug droppings is, well, to identify any bugs present. If your windowsill was fine, those bugs appeared, and suddenly you have a black dot problem, chances are you can put two and two together to figure out what the cause of things is there.

Bugs are also likely suspects because it “makes sense” for them.

Remember how we said that windows are transition points between the indoors and outdoors? Well, bugs are able to take advantage of that as well, and often use windowsills as entry points to homes.

This is also why you need to repair any damage to your windowsill as soon as you spot it. The longer you leave it alone, the more you risk bugs eventually taking advantage of cracks, water damage, and other weak points to wriggle and crawl their way into your home.

Windowsills also typically contain wood, which makes for a nice meal or nesting area for these pests-turned-guests.

Like the awful unwanted guests they are, once inside, bugs can leave little “presents” for you in the form of those disgusting black dot-sized droppings. In fact, in one of the grosser bits of detective work you’re ever likely to do, you can actually determine the bug responsible for this defacement via defecation by using the droppings to tell which type of bug has paid you a visit.

Some telltale ways to identify bugs by their black dot droppings include:

  • Cockroach droppings tend to look like little black pepper balls or a granular shape like the worst coffee grounds ever
  • Termite droppings, on the other hand, tend to be bigger, and can sometimes resemble poppy seeds; however some are also multicolored, which matters since termite droppings can also be used to determine what these literal homewreckers have munched on lately
  • Carpenter ants have small black sawdust-esque droppings
  • Fly droppings tend to be dry, dark, and hard

Besides the fact all of these are obviously quite disgusting, it’s also vital that you get rid of bug droppings for safety and sanitation reasons as well.

Some bug droppings can contain highly contagious bacteria and other sources of infection. Even if they do not, they can potentially trigger allergic reactions, especially in asthma sufferers.

Unfortunately, the more droppings there are, the greater the size of the pest infestation is likely to be. On the other hand, if there are just a few black dots, it may just be a couple random insects, and thus not too much to worry about – once you’ve cleaned up the droppings, of course.

Some rooms are more likely “targets” of black dot bug droppings than others, depending on what the culprits are.

For example, if you have bedbugs, chances are they and their droppings are more likely to be found in, well, a bedroom. By contrast, roaches live and defecate everywhere, though their “leavings” tend to be closest to their nesting and feeding areas, which would naturally point to the kitchen as a likely hotspot.

Flies tend to congregate in damp and dirty spots, so their droppings are most likely to be found on windowsills near trash cans, sinks, and similarly dirty areas.

Identifying Black Mold

How to identify black mold on window sill

By contrast, if you have mold spores on your windowsill instead, they likely got there not via bugs but dampness settling there. This can be due to anything from moisture leaking from elsewhere to the wind blowing damp detritus to the site to rainwater and condensation.

In certain conditions, potted plants and their condensation can give off enough moisture to cause black mold dots to form on your windowsill if you aren’t careful about cleaning the area surrounding them.

The fact that windows are such fertile ground for condensation to occur make them a particularly problematic hotspot for black mold formation. In addition, since windows separate the inside from the outside, there is likely to be different temperatures on either side of the glass paneling, which in turn could aid in condensation and thus black mold.

What’s more, if you cover up your windows with heavy drapes, especially during wintertime, the shade can help create dark warm conditions, which are favorable to black mold growth.

It should also come as no surprise that dirty windows are mold magnets. The dirtier the windows, and the greater the conditions for condensation, the more likely the chance of fungal infections taking root, which in turn can lead to mold.

Dealing with Bug Droppings

First brush window sill before cleaning to get rid of black dots

If your home has been hit by a plague of bug droppings, you may start to feel helpless. After all, insect invaders are nothing if not persistent, so how can you possibly stop them from ruining your windows with their disgusting defecations?

Well, thankfully cleaning away bug droppings doesn’t have to be a Sisyphean task. On the contrary, with the right tools and preparation, you can actually clear away a spate of black dot bug droppings in just a few minutes.

Ingredients you’ll want for this include:

  • A household detergent or all-natural cleaning agent of your choosing
  • Vinegar
  • A cleaning brush
  • A cleaning rag
  • Warm water

To start with, use the brush to remove the droppings from your windowsill.

Once they have been brushed aside, start to apply your cleaning agent. This is essential for killing the infestation at the source and preventing further ones in the future.

After applying the cleaning agent to the site where the black dots were, let them soak in for a couple of minutes so as to ensure that they kill the microorganisms present.

Once you have accomplished this, wet your cleaning rug in the warm water and start to apply it to the windowsill over the affected area. Once again, you’ll want to let things sit for a bit before rinsing everything off again.

One thing you’ll want to avoid doing is using bleach to clear away these stains. Doing so can accidentally discolor your windowsill.

In addition, you’ll want to resist the urge to scrub the problem site too hard. While you want to make sure the cleaning agents really soak in, pressing too hard can accidentally damage the paintwork or coloration around your windowsill.

Once you have soaked your windowsill sufficiently, wipe everything off and let the surface dry again.

What about the aforementioned vinegar?

This is helpful if you really want to make sure you get every last inch of infestation possible. Fans of DIY cleaning solutions know that vinegar mixtures can be used to clean all sorts of problem areas, and this is no different.

What’s more, vinegar is a good alternative to bleach since it does not pose the same risk of discoloring your windowsill.

Once you’ve done all of that, it’s time to start thinking about how to prevent future infestations.

In addition to the preventative methods mentioned above, you’ll also want to make sure that your window and windowsill don’t have any cracks through which bugs might slip. If you do, patch them immediately with caulk or something similar.

You’ll also want to make sure you clean the window regularly.

As mentioned below, one of the biggest potential causes of black dot infestations is to simply let your windows get dirty over time.

Much of those bugs and mold are the root cause of black dot infestations, if your windows are filthy, you unfortunately have to point the finger of blame back at yourself a bit. Neither bugs nor mold can typically trash your windowsill overnight – instead, a massive black dot infestation is both the result of a huge buildup of bugs and mold as well as your own neglect in treating them in time.

To make sure your windows don’t befall such an ugly fate, be sure to clean them regularly so they are less likely to attract insects.

What about pest traps?

While these may seem like a good idea at first, the fact is that most windowsills offer only a very narrow area on which any traps could be placed. Sticky strips can sometimes work if they are narrow enough to fit on the windowsill.

In fact, sticky traps with clear panels are effective since insects can’t tell them apart from the rest of the window. Add an attractive chemical scent to bait the bugs toward the traps, and voila.

Fly traps can work if you have enough space to fit a water pan trap or something similar.

Dealing with Black Mold

As alluded to above, a combination of moisture, darkness, and warmth are all major problem signs for black mold breeding on your windowsill. You can add poor ventilation to that as well, with things such as shades and drapes helping make these problems even worse.

One way to deal with black mold is, thus, to ensure that your windowsill is well-ventilated. The more your windows are exposed to the sun and are aerated, the better the chance that mold spores will die off quickly or simply never take up residence on the windowsill in the first place.

As mentioned above, bleach can be problematic when applied to your windowsill. However, desperate times can call for desperate measures, and if your black mold outbreak is truly in “desperate” condition, bleach can be useful as an emergency solution.

Mix one part bleach with three parts warm water and scrub the black mold off of your windowsill. For this, you’ll want a nylon brush or something similar which, like the cleaning brush in the bug dropping cleaning section, can scrape away all of the mold spores without scratching your window.

Once you are finished, wipe the remaining moisture and residue away with a damp rag. You don’t want lingering moisture to cause still more black mold to form, so make sure the area is dry by the time you finish or soon thereafter.

In some particularly bad cases, it may be necessary to attempt to sandpaper away particularly stubborn deposits of mold. That said, this works best if the windowsill is painted; if it is painted, you’ll need to prime and repaint it after the sanding.

Final Thoughts

Whether they are caused by bugs or black mold, nobody likes having to deal with disgusting black dots on their windowsill.

That said, you don’t have to feel defeated by them, either.

As demonstrated above, there are several ways you can prevent these black dots from ever forming.

It is vital you take these preventative steps, since black dots can be a major hassle and eyesore.

What’s more, as mentioned, they can prove a major health risk. Inhaling bacteria present in bug droppings or black mold spores can have a seriously detrimental effect on your respiratory system and other aspects of your health.

If you do develop a black dot infestation, you should set about cleaning the area immediately. The longer you wait, the worse it will get.

Don’t forget to add a cleaning agent or other form of disinfectant to try and prevent bugs or mold from reappearing.

Once you have done all of this, your windowsill should be black dot-free once more.

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Ed v

Friday 1st of September 2023

I spotted A blaCk pile about the size of cigarette ash. Cleaned it. 2days later there again. Cleaned harder and saw that the wood was soft. Pressed harder and my finger went through. Wood was rotten for about a foot. Soaked it with Clorox clean up. Did the trick. Now to replace.