Insects in the Kitchen Hood: Causes, Remedies, and Prevention

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June 6, 2025 - Updated at June 26, 2025
Tiziano B.
Diagnostics
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With the arrival of spring and rising summer temperatures, the problem of insects in the kitchen hood becomes increasingly common. Ants, flies, and other small insects can easily find their way into the home, especially through less monitored areas like the extractor hood.

Heat, humidity, and grease residue can turn your hood into a real haven for insects. In this guide, I’ll explain why this happens and what are the most effective solutions to eliminate them and prevent them from coming back. Keep reading!

Why Are There Insects in My Kitchen Hood? Here’s What’s Going On

The presence of insects in kitchen hoods is a common issue, especially during the warmer months. If not properly maintained, extractor hoods can become entry points or nesting areas for various types of insects. Let’s take a look at the main causes:

Saturated grease filters: Over time, filters accumulate grease and food residue, creating an ideal environment for insects like flies and ants. Ants are especially drawn to grease, while flies and larvae are also attracted to foul odors.
Missing or damaged non-return valve: The non-return valve prevents outside air—and insects—from entering the hood when it’s turned off. If it’s missing or faulty, insects can get in through the exhaust duct.
External vent without insect screen: If the exterior grille doesn’t have a fine mesh screen, it can allow flying insects and other small creatures to enter. Installing an insect-proof grille is an effective way to block this access point.
Dirty or blocked ducts: The hood’s ductwork can accumulate dirt, grease, and moisture, creating a breeding ground for bacteria and insects. In some cases, it may even house bird nests or other animals, leading to further infestations.

To prevent insects in your kitchen hood, it’s essential to carry out regular maintenance: clean or replace the filters, check that the non-return valve is working properly, and make sure the external vent is fitted with an insect screen.

Immediate Remedies Against Insects in the Kitchen Hood

When you discover insects in your kitchen hood, it’s crucial to act immediately to eliminate them and prevent their return. Here are the most effective DIY remedies you can apply right away:

Remove and clean the grease filters: Grease filters trap oil and food residues, which attract flies, larvae, and ants. That’s why it’s important to wash them regularly using hot water and a degreaser.
If your hood is recirculating, replace the activated carbon filters: These filters absorb odors and vapors. When saturated, not only do they lose effectiveness, but they can also become a trap for dirt and attract insects. Some filters need to be replaced, while others can be regenerated periodically to ensure clean air and a hygienic kitchen.
Check the non-return valve: The non-return valve prevents air (and insects) from entering the hood from the outside. If it’s broken, stuck, or missing, replace it immediately with a compatible model.
Install a vent cover with insect mesh: If the hood’s exhaust vent is exposed outside, it should be equipped with a fine-mesh screen. This prevents flying or crawling insects from entering the ducts. There are universal models on the market that are easy to install.

Once you’ve eliminated the insects already present, it’s important to focus on prevention to keep the problem from coming back when the warm season arrives.

What Diameter Should the Insect Mesh Have?

The mesh should be fine, with an opening size between 1 mm and 2 mm. This is ideal for blocking flies, mosquitoes, wasps, and other flying or crawling insects that might enter through the external ducts.

According to guidelines from various manufacturers of home ventilation accessories, a 1 mm metal or fiberglass mesh is recommended as the best balance between:

insect protection
optimal airflow
long-term resistance to weather conditions

The material also matters: stainless steel or anodized aluminum meshes are more durable and weather-resistant. Fiberglass meshes coated with PVC are more affordable and easier to install, but they have a shorter lifespan.

Can I Spray Insecticide Inside the Kitchen Hood?

No, spraying insecticide inside the kitchen hood is not recommended. Even if it seems like a quick fix for insects, using chemical products inside the hood or its ductwork carries significant risks for both your health and the appliance. Here's why you should avoid this practice:

Toxic residue in cooking vapors: The hood’s job is to extract and filter the air generated during cooking. Any insecticide residue inside the ducts or filters may be released into the kitchen air and potentially contaminate food.
Flammability risk: Many spray insecticides contain flammable propellants (like butane or propane). Spraying them near heat sources or cooking vapors increases the risk of fire or explosion—especially near open flames on gas cooktops.
Damage to internal components: Filters, fans, and electronic boards are sensitive to chemical solvents. Insecticide spray can corrode or compromise these parts, reducing the hood’s efficiency or causing malfunctions.
Short-term effect only: Insecticides kill only the visible insects. If the root cause isn’t addressed, the infestation will return.

Can Flies Lay Eggs in the Hood Filters?

Yes, unfortunately, flies can lay eggs in the hood filters—especially if the filters are saturated with grease and not cleaned regularly. Kitchen hoods extract vapors and cooking residues rich in grease and organic particles, creating a warm, humid environment that can favor insect proliferation.

Since filters are often out of sight, it's easy to overlook their hygiene, allowing eggs to hatch and larvae to appear. You might notice the problem through the presence of:

Unusual odors coming from the hood, even when it's off
Larvae (white worms) in the filter area
Adult flies emerging from the hood or gathering around it

To avoid these unpleasant situations, prevention is key—as we’ll see below.

Long-Term Prevention Against Insects in the Kitchen Hood

After dealing with an insect infestation in your kitchen hood, it’s essential to take preventive measures to ensure the problem doesn’t return. In addition to installing an insect-proof grille and checking the non-return valve, as discussed above, here are other key precautions to consider:

Regular maintenance of the filters: Grease filters should be cleaned every 2–3 months using hot water and a degreasing detergent. Many of these filters can be washed in the dishwasher, but it’s always best to follow the manufacturer’s instructions. Activated carbon filters, on the other hand, should be replaced every 6 months (for standard models) or regenerated every 3 months (for Long Life types).
Annual cleaning of the ventilation duct: Over time, the duct can accumulate grease and debris, making it a potential entry point for insects—or even small birds. A thorough cleaning should be performed at least once a year. For best results, rely on professional services to fully remove buildup and restore optimal airflow.
Checking seals and joints: Poorly sealed joints or cracks can allow insects to enter the hood’s ductwork. During maintenance, carefully inspect all connections and seal any gaps using heat-resistant silicone or similar materials to prevent unwanted access.
Cleaning the internal and external surfaces of the hood: In addition to the filters, the inside and outside surfaces of the hood should also be cleaned regularly to remove grease buildup and avoid creating a hospitable environment for insects. Use a soft cloth and a non-abrasive cleaner, following the manufacturer’s guidelines to avoid damaging the materials.

By adopting these preventive steps, you can keep your kitchen hood efficient, hygienic, and far less prone to insect infestations.

Filtro Cappa: New Filters and Spare Parts for Your Kitchen

To prevent insects from appearing in your kitchen hood, it’s essential to keep your extraction system in perfect working order. This means not only regular cleaning, but also replacing worn-out filters and components as needed.

Over time, old filters lose their effectiveness and need to be replaced. At Filtro Cappa, you’ll find a wide range of filters and spare parts—even for older or discontinued models. Our catalog is designed to offer effective and affordable solutions for every situation.

Do you have an older hood and fear that spare parts are no longer available? Contact us: we’ll help you find the right replacement parts to extend the life of your appliance, ensuring hygiene, safety, and protection against unwanted guests. You can reach us on WhatsApp or by email: we’ll get back to you as soon as possible!

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