Complete Pest Control Guide for Apartments

Even if you keep your apartment clean, insects can still find their way inside. The right response depends on the type of pest, and the places where they are likely to appear also vary. In this article, we explain how to deal with insects in apartments by pest type and by location, along with the basic approach to who should bear the costs.

Where do insects get into a room from?

Insects do not "appear out of nowhere." There is always a route by which they enter. Understanding the main entry points is the first step in prevention.

Through the entrance and door mail slot

Mosquitoes, flies, and gnats often come in with you when you return home, and they also frequently enter through gaps around the door mail slot.

Through windows and the balcony

If a screen is warped or torn, insects can enter through the gaps. By design, the screen should generally be positioned to the right, because placing it to the left makes gaps more likely.

Through vents and exhaust fans

Ventilation equipment connected to the outside can serve as an entry route for insects. Older apartments may not have filters, so this is something you should check carefully.

Through drains and air conditioner hoses

Cockroaches feed on food scraps and grime in drains, and they can also enter through the air conditioner's drain hose. Regular cleaning and inspection are effective.

What makes an apartment more likely to have insects?

It is important to assess pest risk even at the property selection stage.

• Close to restaurants, convenience stores, or garbage collection areas：Flies and cockroaches that gather around food and waste tend to be more common
• Close to parks with abundant greenery or nearby water：Stink bugs and centipedes are more likely to appear
• Many gaps and low airtightness：Wooden buildings and older properties require extra caution
• Poor airflow and limited sunlight：Moisture makes it easier for insects to thrive

Why are first-floor apartments more prone to insects?

First-floor units are close to the ground and garbage areas, and they often get less sunlight, which makes moisture build up more easily. This creates an environment where crawling insects such as ants and centipedes can enter more easily, and where moisture-loving pests such as mites and cockroaches are also more likely to gather.

How should you deal with insects that commonly appear in apartments?

Cockroaches

Because their breeding season peaks during the rainy season, it is effective to use a fumigation product in May and then use it again two to three weeks later. Place poison bait around likely entry points such as the entrance, balcony, and the outdoor unit area of the air conditioner.

Flies and gnats

Rotting food and garbage are common sources. Switching to lighting that emits a yellowish tone or to insect-resistant fluorescent lighting can be effective. It is also important to remove moisture thoroughly from the kitchen.

Mosquitoes

Standing water on balconies or in gardens becomes a breeding site. Using mosquito coils after rainfall is effective. Aromatic oils such as peppermint and lemon-based oils also have a repellent effect.

Mites

They are difficult to see with the naked eye and tend to settle in bedding. Regularly sun-dry pillows, futons, and carpets, and keep humidity under control. After treatment, be sure to vacuum up carcasses and droppings, as they can trigger allergies.

Ants and termites

For ants, storing food indoors in sealed containers is effective. Termites tend to appear in April and May, and spraying insecticide in areas where they can easily enter, such as toilets, bathrooms, entrances, and underfloor spaces, helps with prevention.

Spiders and centipedes

Spiders can be kept out by installing filters on exhaust fans and drain openings. For centipedes, removing other insects is an indirect but useful countermeasure. Applying dedicated chemicals can also be effective.

What pest control measures should you take immediately after moving in?

• Fumigation-type insecticide：It is most effective when used in an empty room before furniture is moved in
• Check the screens：Make sure there are no small holes or warping, and consult the property manager promptly if there is damage
• Seal gaps：Attach filters to vents and exhaust fans, and check for gaps around drain pipes
• Prepare insecticides：Keep multiple insecticides on hand that match the types of pests you may encounter

What pest control habits can you practice every day?

• Clean regularly and do not leave behind food scraps, dust, or hair
• Dispose of unused cardboard boxes, as they can become a breeding ground for cockroaches and mites
• Do not let garbage pile up, and throw it away regularly
• Store food in the refrigerator or in sealed containers
• Place herbs such as peppermint, eucalyptus, and lemongrass near the entrance or in the kitchen
• Choose houseplants that are less likely to attract insects, and wash water trays regularly

What measures work best by location?

• Kitchen：Throw away food waste every day and clean the drain regularly
• Bathroom：Rinse with cold water after bathing to lower the temperature and dry the space thoroughly
• Entrance：Place insect-repellent items or herbs there, and switch the lighting to LED
• Air conditioner：Clean the filter each season and attach an insect-prevention cap to the drain hose

For more on managing equipment in rental properties, you may also find The Complete Guide to Pre-Move-In Checks That Determine the Success of Rental Management helpful.

Who pays the extermination cost when pests appear?

If the cause is the tenant's lifestyle habits, the tenant generally bears the cost (a breach of the duty of due care), while if the cause is a defect in the building or equipment, or if pests appear immediately after move-in, the landlord generally bears the cost. If the lease agreement clearly specifies how costs are divided, that provision takes priority.

How do you choose an apartment where insects are less likely to appear?

• RC construction (reinforced concrete)：It offers better airtightness and fewer entry points for insects
• Within 5 years of construction：There is less equipment deterioration and fewer gaps
• No door mail slot：This removes one of the possible entry routes
• Third floor or higher：This exceeds the height that insects can typically fly to on their own, which is around the second floor
• Good sunlight and ventilation：Moisture is less likely to build up, creating an environment where insects are less likely to live

Frequently Asked Questions (FAQ)

If you see a cockroach, what should you do first?

After killing the insect with a jet-spray insecticide, place poison bait along likely entry routes. If there is a possibility that they have already begun breeding, use a fumigation product to treat a wider area.

What should you do if you are bitten by mites?

If the itching is severe, we recommend visiting a dermatologist. Drying bedding in the sun and then vacuuming up mite remains can help prevent the problem from recurring.

If termites appear, should you contact the landlord?

Yes. Because termites can damage the building itself, you should report the issue promptly to the property management company or landlord. In general, the owner bears the cost of exterminating pests that affect the building's structure.

If you are uncomfortable with insects, what should you check during a viewing?

Check the building structure, such as whether it is RC construction, along with the building age, floor level, whether there is a door mail slot, and the surrounding environment, including proximity to restaurants, parks, and water. Ideally, you should also check the condition of vents and exhaust fans.

Why do cardboard boxes become a breeding ground for insects?

Cardboard provides the right amount of moisture, darkness, and crevices, creating an environment where cockroaches, mites, termites, and booklice can multiply easily. For that reason, we recommend not storing them long term and replacing them with commercially available storage boxes.