Ants are a type of insect that can be widely found in areas from the tropics to the subarctic. They live well in general conditions in agricultural and residential areas. There is a saying that ants occupy most areas in the world. It has been estimated that there are 15,000 identified types of ants throughout the world. In Thailand, the Faculty of Forestry, Kasetsart University has reported that 9 subfamilies, 86 genuses and 512 species of ants have been found. Ants are a type of social insects with living conditions different from other insects. Normally, there are two levels of social insects; 1.) Hymenoptera which includes bees, wasps, hornets and ants. 2.) Isoptera namely termites. Ants are social insects in Formicidae family. Ants are true high-level social insects. A huge amount of ant population live in their nests. Nests are finely and carefully constructed. Members in their nests are clearly divided into different casts. These are clearly seen in their bodies, features and duties. They communicate among themselves in their nests. Ants affect humans in many ways. They are insects that destroy agricultural crops in plantations and in storage areas. They damage livestocks by eating larva. In households, ants come in to annoy and damage. They come in to share food and habitat with human beings. Moreover, ants may directly harm human beings as some species are able to bite or attack with stings or they may do both causing pains and allergies. An infectious injury may occur in the area that has been bitten or attacked. From the said reasons, ants are an enemy against medical and agricultural sectors. Apart from causing issues to human beings, livestocks and agricultural areas, ants also create problems in various industries as they go in to live in various electronic tools and equipment causing enormous damage.
General Features of an Ant
External structures of an ant include the head, trunk and gaster. Each part consists of certain organs or significant features. These features differ depending on different types of ant. Other features of an ant that clearly differ from other insects are geniculate antennae which can be divided into scape and funicle. The number of antennae joints for a female ant ranges from 4-12 while that for a male ant is between 9 and 13. An ant has a chewing mouth with teeth or molar called mandible. Some ants have huge teeth that can be seen clearly. The first abdominal section of an ant combines with the third trunk section called Propedeum. The second or third abdominal section of an ant is abdominal pedicel which may include lumps or not. The rest abdominal sections are called gaster. Some female ants have stings that stick out from the end of their abdominal sections. An ant has one pair of compound eyes. Some ants have one eye called Ocelli. Generally there are three eyes above and between compound eyes. Single eye does not function as a vision receiver.
ants are insects with complete metamorphosis. Their life cycle includes phases of egg, larva, pupa and adult. As ants are social insects, ant members in their nest are clearly divided into different castes namely;
1. 1. Queen:
The queen is larger than other ants in the nest. The queen has huge trunk and large abdominal section. The queen ants usually have single eyes. They are able to reproduce. Their duty is to start constructing nest and lay eggs to produce other members of different castes in the nest. The queen controls various activities in the nest. Following one breeding, the queen is able to lay eggs throughout her life. Once the queen dies, the whole nest of ants will later collapse because there are no new workers to feed other ants in the nest.
2. 2. Breeding ants:
consist of male and female ants that are able to reproduce. Generally, they have wings. They are larger than workers but smaller than the queen. This caste of ants is produced when the nest is large and there are a lot of members in the nest. Their duty is to reproduce to build new nests. Their number is smaller than workers in a nest.
3. 3. Workers:
These are infertile female ants with no wings and eyes. They seek food and are normally found outside their nests. Apart from food duty, workers are also responsible for building and protecting their nests, looking after larvas and the queen. They may live as long as 7 years.
Ecological Information (Behaviour)
Ants have been in this world for a long time. From the study of fossils, scientists believe that they were here more than 50 million years ago. They are insects with high evolution level. They have been able to adjust themselves to the environment and have survived through the ages. This is because they have behaviour that are conducive to living. Such behaviour includes;
1. Reproduction and Nest-building
Once the population of ants in a nest is very dense and there is a need to expand the nest, breeding ants both male and female will fly out of their old nest to mate with other ants from other nests. Workers help to make holes that are used as ways out by breeding ants. Ants with high evolution level mate and breed at a high level for instance on a tree. Those with low evolution level breed on the ground. After breeding, only the female ants will look for appropriate places to build nests. This differs depending on ant species. Once a suitable place has been found, a new nest will be built. The female ant will leave her wings and become a queen. Then she will start laying eggs. The first egg laying is in small groups. The first generation of ants consists only of workers. The queen feeds the first set of larva herself with non-fertilised eggs until the first set of workers are able to find food. When there are more fully-grown workers, the queen will only lay eggs and control behaviour and activities within her colony. Seasons and climate for instance the temperature, humidity as well as food fertility affect the breeding conditions. Once the colony is more fertile, the queen will produce male and female breeding ants to further expand the colony.
2. Food behaviour
Ants find food day and night. They consume diverse types of food. They eat other living or dead organisms as well as seeds or suck liquid. Some workers are able to store liquid food inside their stomach and distribute it to other members in their colony by disgorging it out within the period of 20 hours.
Ants communicate by releasing pheromone in which other ants detect using antennae and the front pair of leg. There are many types of pheromone for instance, navigating, alarming and other types of pheromone which are released at different circumstances.
Some ants use voice to communicate. Such voice is used to warn other members to come together when an enemy is found or to call others to help at a time of danger.
Important types of ants
1. Fire Ant
Important Features: They come in yellow-red colours with hair on their heads and trunks. There are ten joints in each of their antennae. A trunk of a fire ant is narrow. The first section is round. Its abdomen is round like an egg with brown stripes across its body. A fire ant has sting to fight against their enemies. Its body is 7-8 millimetres long.
Biological Features: They have their colonies under loose soil using sand soil. Their colony looks like a small soil hill. A colony has several entrances and exits through small holes on the ground. They like high-protein food. They consume insects and carcasses of small animals as well as leftover food from human beings.
Medical Significance: They harm human beings by biting and using their stings. Their victims will feel burn-like pain hence the name fire ant. After being stung by a fire ant, the wound will swell and become red. The actual point of stinging is clear like a burn wound. One will feel really itchy and once the wound is scratched, the would will swell and expand.
2. Pharaohs Ant
Important Features: A Pharaohs Ant is yellow to light brown or bright red. Its abdomen is of dark colour and almost black. There are 12 joints in each of its antennae. It has small eyes. It has hair all over. Its trunk is long and narrow. The body is 1.5-2 millimetres long.
Biological Features: Pharaohs ants have a mother colony and daughter colony/colonies near food sources. They are found in houses. These daughter colonies are hidden along cracks in walls, cracks along the wall and light switch boxes. These Pharaohs ants eact a variety of food be it sugar or protein. They are difficult to control because of their small size allowing them to hide very well when they find food further away from their colonies. They have both mother and daughter colonies making them difficult to find. It has also been found that spraying chemical into any one of their colonies will make their population dispersed. Sometimes, they disperse into smaller colonies called budding making it even more difficult to control.
Medical Significance: Pharoahs ants have stings but they are not visible. When they are disturbed, they will protect themselves by biting. The victims only feel a bit of pain and itchiness.
3. Ghost Ant
Important Features: A ghost ant is rusty-red and dark brown in colour. Its abdomen is clear. There are 12 joints in each of its antennae. Its trunk is long and narrow. Its body is 2.5-3.5 millimetres long.
Biological Features: Ghost ants have their colonies in the ground. They are found in houses and accommodation. They like sweets. When they have consumed food, they will release some excrement causing the flavour of the food to change. They move quickly.
Medical Significance: When they are bothered, they will protect themselves by biting. The victims only feel a bit of pain and itchiness.
4. Crazy Ant
Important Features: A crazy ant is dark brown with some parts black in colour. It has yellow-brown hair all around its body. There are 12 joints in each of its antennae. Its abdomen is of egg-like shape. Its body is 2.3-3 millimetres long.
Biological Features: They can be found all over the places both in buildings and outside. Workers find their food further away from their colonies. Thus it is difficult to control this kind of ants. They move very quickly and do not follow pheromones of other ants. They are found around the world. Their colonies are along the cracks of trees or in the ground or under objects. They like sweet liquids. Sometimes they are found transporting eggs. This type of ant does not harm human beings even though they are being disturbed.
Medical Significance: Crazy ants cause annoyance more than danger to human beings.
5. Big-headed Ant
Important Features: It is dark brown in colour. Its molar is huge to allow them to crack open seed shells or external bones of insects that have fallen victims. There are 11 joints in each of its antennae. The first and second sections of its trunk clearly bulge out. Its abdomen is wide and is of egg-like shape. Its length is 4.5-13 millimetres.
Biological Features: They have colonies in loose ground. One only sees small openings in the ground with loose soil around the edges of entrance holes. They like to build colonies in a damp and shaded area. They consume insects and meat.
Medical Significance: They harm human beings by biting. The symptoms following the biting is very similar to that of a person bitten by a fire ant.
6. Green Tree Ant/ Weaver Ant
Important Features: It is rusty-red in colour. Its head and trunk are covered with short white hair. There are 12 joints in each of its antennae. It has a long trunk. Its first trunk section bends outwards. The second trunk section narrows down like a saddle. Its third trunk section is round. Its legs are long and slender. It is 7-11 millimetres long.
Biological Features: This type of ant have their colonies on big trees like mango or rose apple trees. Leaves are used to build ant colonies. Larvas release sticky substance to join leaves. They bite their victims and release poison from the end of their abdomens. When their victims are injured, they will drag their victims back to their colonies.
Medical Significance: When they are disturbed, they will harm human beings by biting. The person bitten by this type of ant will feel a lot of pain. Then the wound will swell and the person will feel itchy.
Green Tree Ant/ Weaver Ant
Methods to control ants
In order to control and eradicate ants effectively and sustainably like the methods used against other insects, firstly, one needs to know the type of ant that we want to control. We also need to know their features, habits, food and habitats. This is to find appropriate methods to eradicate each type of ants. One should use a combination of methods. The typical ways to control ants are;
1. Chemical Control
1.1 Use chemicals that can be easily found in households for instance lubricants and vinegar. Drop the liquid into holes that are used by ants. These chemicals are able to kill these ants.
1.2 Harmful chemicals used in typical households- Most of them are synthetic pyrethroid or hazardous materials with residual effects in organophosphate and carbamate groups.
1.3 Toxic Baits- Using toxic baits is one of the best methods to control and eradicate ants. A good bait must not have any repellent but consists of food that attracts ants to come to the bait as well as chemicals that are able to kill ants and substance that is able to mix with the bait and still retains good conditions. The food that is mixed in toxic baits differs. It may be protein or sugar. Hence one should choose food that is appropriate to the types of ant that like different types of food. Normally, chemicals that are mixed in a toxic bait to kill ants can be divided into 2 types; quick release which kills ants immediately giving quick results; and slow release chemicals which give slower results but are good in the long term as ants will bring toxic baits back to feed members in their colonies (trophallaxis). Ants in other castes including larvas in the colony will also die. Toxic baits should be put in proper places and in more than one place for instance the path that ants use to find food and a place close to water source. Toxic baits have to be continually placed and regularly changed. One needs to make sure that there is no other type of food apart from toxic baits.
2. Environmental Adjustment Control
Make sure that there is no food sources in a household or around the house. One needs to take good care not to allow any place suitable for ants to build their colonies. One should not grow trees with honeydew near the house as some ants rely on honeydew on trees or they have a mutual relationship with aphids that suck in honeydew from the trees. At the same time, ants receive food released from aphids. Hence, if one grows trees with honeydew near the house, ants will find ways to come or build colonies in the house.
3. Manual Control
Killing ants by hands. One may use a broom to sweep ants away. One may also destroy ant colonies by fire or dropping them if the colonies are up in the trees.