Termites, like ants or bees, are social insects that live mostly in subterranean colonies. Their organization, their ability to degrade wood and materials containing cellulose make them formidable enemies for buildings. Termites are divided into several castes: workers, soldiers, and breeders. It is the workers who provide the food needs of the colony: they will harvest the cellulose which is mainly in the wood, cardboard, paper, etc. After having swallowed the wood, they redistribute digested food to the rest of the colony.
Underground termites form underground colonies in the soil. Their favorite food is dead wood, but they can attack any material containing cellulose (paper, cardboard, plasterboard). The breeders can settle directly in the support that acts as a source of food. Several feeding sites can be exploited: pyres, stumps, fences, houses, communicating with each other through a network of galleries or tunnels.
The presence of water is obligatory for the development of subterranean colonies. At the end of winter or spring, adults try to colonize new territories. Most, however, remain close to the point of flight, termites fly very badly. The couples who form on this occasion can found new colonies. Dissemination of termites can also be achieved through the displacement, voluntary or otherwise, of part of the colony. Replacement breeders from nymphs or workers appear.
Constantly fleeing light, termites are hard to spot. The appearance of a swarm in or near the house is a first indication of the presence of a termite colony in the vicinity. The constructions of the workers are characteristic and easily recognizable. The most common are tunnels traversing the surface of walls, wood or soil. They are also called galleries and consist of a mixture of soil, excrement, and saliva.
When degradation is advanced, the damage can be evidenced by a simple pressure exerted on the pieces of wood hollowed out, of which the outer appearance is often preserved. Degraded wood often has a laminated appearance, with termites ingesting the softest parts of the wood first, leaving behind the harder rings. Termites also move in plaster walls, piercing the wall coverings of small holes regularly, which they fill with soil. These plugs, sometimes as big as a pinhead, isolated or not, can diagnose the passage of termites in the walls.
Termite control methods and products have evolved considerably over the last decade.
- The chemical barrier: It has been in use by specialized treatment companies in the fight against termites. It consists of creating a system of impassable chemical barriers between the building to be protected and the ground, natural place of the life of the subterranean termite. In this technique, three insecticide barriers located at ground level, load-bearing walls, partitions and doublings, structural wood and frames, allow a durable protection of the construction.
- The physicochemical barrier: Introduced more recently, this technique is implemented as part of a construction where it replaces the application of an insecticide product. The only product currently marketed consists of a polyethylene film, on which is grafted an insecticidal active ingredient. This film also provides protection against rising damp. The installation requires particular care in order to leave no area of soil not covered by the film. At the level of the reserves (drains, evacuation of water ...), insecticide granules of the same nature as the film allow a clogging of the openings which will not be covered by the concrete slab.
- Insecticide traps: while the above techniques are aimed at protecting the building, insecticide traps also target insects directly by attempting to eliminate colonies or termite mounds. Their operating principle is based on the social behavior of the insect; when worker termites look for cellulose, they come into contact with the traps (containing an appetizing substrate) installed regularly around and inside the property to be protected and create a food communication route with the whole colony. By introducing into the "connected" traps an insecticide product with well-defined characteristics, the
- Regarding the different possible treatments, the choice will be made according to the state of the ground and the frame that one wishes to protect.
- On unbuilt land: Insecticide traps, because they aim to eliminate the colonies present in a limited territory, are well suited to the case of undeveloped land. However, they cannot prevent the recolonization of the area treated by another termite colony after a few months or years if favorable conditions arise. This is why it is recommended to ensure permanent monitoring of the decontaminated area in order to intervene as quickly as possible if new infestations appear.
- Pre-construction precaution: Lands colonized by termites and intended to receive a construction can be treated with insecticide traps to eliminate insects present. But because of the re-infestation always possible by another colony, the protection of future construction can only be effectively ensured by the implementation of additional means.
- Post-construction prevention: In sensitive areas where the presence of termites is a permanent risk, the implementation of chemical barriers at ground level, walls and woods especially on the ground floor is currently the safest way to protect the building. Indeed, insecticide traps currently on the market do not have the ability to attract and direct all individuals of a subterranean colony on the food substrate they contain because the foraging of termites’ workers will lead them almost inevitably to various sources of cellulose (building, trees, old stock, traps).
Insecticide traps aim at eliminating the subterranean termite colony attacking the construction. Their implementation is relatively easy and does not cause inconvenience to the occupant. Similarly, given the small amount of insecticide contained in the traps, they pose no particular risk to the environment. On the other hand, given their mode of action that integrates the biology and social behavior of termites, the traps have a variable efficiency depending on the species and a reaction time that can reach several months before the elimination of the colony.