Although ants in most cases are considered as beneficial insects but they are pests in the following aspects:
Most people would accept if ants are foraging outside of their house.
But if they appear in great numbers in our living halls, kitchens, bathrooms, bedrooms and so on, they become nuisances to us.
Myrmecophobia is a term refer to inexplicable fear of ants.
As they forage in great numbers and most of them like sweet, fatty and protein foods which are easily available in our kitchens, they spoil our food.
Also because of their tiny size, they can easily access to our food stuffs no matter where you keep them.
Some ant species, when disturbed, would bite and sting.
Most ants spray or inject a substance from the abdomen called formic acid that cause a burning sensation.
Severe allergic reactions can be caused by ant stings which could lead to symptoms such as chest pain, nausea, heavy sweating, loss of breath and so on which can be fatal if not treated.
Because of their hairy bodies and foraging behaviour, ants normally carry bacteria, fungi or viruses on their bodies.
Some places like hospitals, restaurants or our kitchen areas must be in germs-free conditions.
Many ant species are known to cause food contamination, contamination of surgical instruments in hospitals and so on.
Most ant species like to feed on honeydew.
Honeydew is a sugar-rich sticky liquid secreted by insects like aphids, mealybugs and scale insects after they feed on plant sap.
In order to get continuous supply of honeydew, many ant species farm these insect pests on plants in our gardens which might eventually kill the plants.