They are strong and numerous and no matter what kind of security system you have, there's no way you can stop them from marching into your home. Thank goodness they're small.

Of course, we're talking about ants, the tiny intruders who have no respect whatsoever for the owners of the house. In large numbers-and right in front of your eyes-they tramp across your floor, climb up the wall and even onto your dinner table. Basically, from the kitchen to the bedroom, there's not a single place you can really claim as your "private" space.

Most of the ants you come across are the workers, the sterile females who are destined to do the foraging and all kinds of labour for the colony-which also includes one or more queen(s) as well as the eggs and pupae. Male ants are very few and each of them are short-lived. Their sole purpose of life is to mate with a potential queen and die.

Each queen is fertilised just once and that's already enough for her to act as an "egg machine" for the rest of her life. An ant queen hides deep in the nest, which is usually located underground outside people's houses. She can live for as long as 10 to 15 years.

Meanwhile, the lives of the workers, her offspring, can last from several months up to about seven years, depending on the species and provided they are not squashed or sprayed to death while carrying out their tasks outside the nest.

Well, at least we, Homo sapiens, are lucky that most of the world's ants live in the forests-of about 10,000 or so species described, only a few dozens make people's houses their foraging grounds. And even fewer actually nest in our abodes.

Like the rest of the world, Thai households are frequented by different kinds of ants. However, we tend to call them just by their colour, which is why they are generally, and simply, categorised as either mod dam (black ants) or mod daeng (red ants).

But exactly what species do these insects belong to? Considering that they share the house-and sometimes even the bed-with us, it's better to know who they are, right?

One problem is that nobody really knows. Ant researchers in Thailand have been focusing on forest-dwelling species and on those living in agricultural environments. However, with kind help from the entomologists at Kasetsart University, several of the "house ants" have finally been identified.

Scientists use Latin when they refer to living things, and ants are no exception. At first, these weird names may seem impossible to remember. But don't panic. Try reading them aloud a few times and you'll be amazed at how quickly your brain will learn to recognise them as they did with such simple words like "black ants" and "red ants".

Some species also have English common names which prove a really big help. Several of these ants can be found in human settlements around the world, thanks to centuries of overseas trade.

Let's start with one of the most common: Paratrechina longicornis. These are those little, about two-millimetre-long, black ants, which like to crawl on sweet stuff. (If that doesn't ring a bell, take a look at the photo that accompanies this article.) The ants are also called "crazy ants" because of their erratic movement.

Another group of black ants is Technomyrmex sp-they are about the same size as Paratrechina and to untrained eyes look very similar. However, the species is not often found in the house, but around it-in the lawn and on the garage floor, for example.

Those two ants do not bite. But this one does, and it stings too: Solenopsis geminata-the "fire ant". These are red in colour and the workers come in two forms and sizes: the major form is about five millimetres long and the minor form (which is actually the majority of the colony) measures two to three millimetres.

Normally the Solenopsis stay outside our houses, but whenever they know there's something to eat, they do not hesitate to march, in a well-organised line, into the house towards the food source.

Perhaps the most cosmopolitan species is the Monomorium pharaonis. These tiny, one-millimetre-long, yellowish brown ants are also called "Pharaoh ants", probably because they were described from specimens collected in Egypt. Wherever there are bits of food-in ordinary houses or high up on tall buildings-you can always expect to see them.

Another yellowish brown species is Tapinoma melanocephalum. These very small ants usually emerge from cracks and holes in the wood. One thing about them that's easy to remember is that they give you stinky fingers when you squash them.

Two other species found in urban areas were also identified, namely, the dark brown Tetramorium ruflonigra and the red Pheidole sp ; a few more could have been recorded if there had been more time to collect specimens.

Despite their ubiquitous presence, humans seem to find ants more tolerable than other unwelcomed guests such as cockroaches. In fact, a lot of people do not mind eating food that has a few ants on it (although they usually get rid of the ants first).

The practice usually causes no harm but you'd better keep in mind that before the ants finally end up on the food they might have travelled through places so dirty you wouldn't have walked on them yourself.

Come to think of it, while ants that crawl on our dishes may not do the food any good, those crowding around rice grains or cockroach carcasses on the floor are actually doing us a service, ridding our house of unwanted organic matters we failed to properly dispose of.

Still there may be times when the ants show up in tremendous numbers and you decide to declare war.

In such a situation, some people "instinctively" grab a can of insecticide and spray at these six-legged invaders. But doing so will kill just a fraction of the colony's workers. There's no way you can destroy the entire colony unless you trace down the queen and the nest, which is usually located away from your house.

Besides, using deadly chemicals in your residence tends to do more harm to your family than to the ant colony.

A wise way to live in this ant-infested world is to always keep your home dry and tidy and make sure food is kept in the right places-like in tight containers or in refrigerators. In the old days, Thai people prevented the insects from making their way up and into their food cabinets by placing the cabinet's four legs in bowls filled with water-ants can't swim and thus can't reach the yummy stuff.

The techniques may vary from one generation to another, but one thing never changes: The more we know about these creatures, the better we can learn to live with them.

Sounds like your spouse, huh?

- Special thanks to Associate Professor Decha Wiwatwitaya of Kasetsart University's Laboratory of Forest Entomology and Dr Chitapa Ketavan of Kasetsart's Department of Entomology.

- W.H. Robinson (1996). Urban Entomology: Insects and Mite Pests in the Human Environment. Chapman & Hall.

- Bert Holldobler & Edward O. Wilson (1990). The Ants. Springer-Verlag.

- Bernhard Grzimek (1975). Grzimek's Animal Life Encyclopaedia. Van Nostrand Reinhold Company.