Pharaoh Ants: Why They Are Hard to Eliminate

Pharaoh ants are tiny, pale yellow to reddish-brown ants that turn up in kitchens, bathrooms, hospitals, hotels and offices across the tropics. They have a reputation among pest controllers as one of the hardest ants to eliminate, for reasons that have everything to do with how their colonies work.

This guide explains why, and what does work.

The short answer

Pharaoh ants live in colonies with many queens, and nest in many small satellite nests in hidden, warm places such as wall voids, behind tiles, in electrical equipment and cupboards. When disturbed by sprays or repellents, they split into new colonies, a behaviour called budding, which spreads the infestation. They also feed on a wide range of foods, change preferences and travel along long trails. The effective approach is to avoid spraying, use carefully chosen slow-acting baits that workers carry to all nests, maintain baiting for weeks, improve sanitation and seal entry points, and call professionals for persistent cases.

How to recognise them

• Very small, about 2 mm, with a pale yellow to light reddish-brown body and a darker abdomen.
• Slow-moving, trailing in lines.
• Found in kitchens, bathrooms, near sinks, and in warm, humid places.
• Not usually aggressive, but they can contaminate food and surfaces.

Why they are hard to eliminate

1. Many queens: Colonies have several or many queens, so killing one does not end the colony.
2. Budding: When stressed, groups with queens split off and form new nests nearby.
3. Hidden nests: Many small nests in voids, electrical boxes and furniture.
4. Wide diet: They eat sweets, fats and proteins, and switch preferences.
5. Repellent sprays: Can trigger budding and scatter colonies.

Where they cause problems

• Homes: kitchens, bathrooms, bedrooms and wall voids.
• Hospitals and clinics, where they can reach wounds, dressings and equipment.
• Hotels, restaurants and offices.
• Electrical and electronic equipment, causing faults.

What does not work

• Spraying trails and nests with repellent insecticides.
• Killing only the visible ants.
• Short, one-off treatments.

What works

1. Baits, used carefully: Slow-acting baits, in gel or liquid form, placed along trails and near suspected nests, so that workers carry them to the queens and brood.
2. Offer choices: Provide different baits (sweet and protein or fat) to see what the ants prefer, and switch if needed.
3. Patience and consistency: Baiting can take weeks. Replenish baits and do not disturb the trails.
4. No spraying: Avoid repellent sprays in the treatment area.
5. Sanitation: Remove food and water sources, and store food securely.
6. Seal gaps: After control.
7. Monitoring: Check baits and trails, and follow up.

Professional help

Pharaoh ant control is usually best handled by professionals, who can identify the species, plan the baiting and monitor. In sensitive places such as hospitals, a coordinated plan is essential.

Safety

• Keep baits out of reach of children and pets.
• Place baits away from food preparation surfaces.

Frequently asked questions

Why do they come back after spraying?

Spraying scatters colonies and does not reach the queens.

How long does baiting take?

Often weeks.

Are pharaoh ants harmful?

They can contaminate food and carry germs, and cause faults in electronics.

Can I do it myself?

Mild cases may respond. Persistent ones need a professional.

This guide is part of IPest's complete resource on ant control. For identification help, prevention and treatment options, see our full ant control guide for Bangalore.