Termites have three different castes, each of which performs different roles within the colony. These castes include reproductives (including kings, queens, and primary and secondary reproductives), soldiers and workers. Each caste has unique physical features to help it fulfill its role in the colony.
In general, workers and nymphs are soft-bodied and look like larvae. Soldier termites have soft bodies with hard, enlarged heads and large jaws (mandibles) that help them protect the colony. Fully mature, reproductive termites have wings and hard bodies that prepare them for leaving the nest to start new colonies.
While there are broad descriptions of what each termite caste looks like, not all members of a caste look exactly alike. There are variations in size and color between termite species. For example, western subterranean termite soldiers have yellowish heads, while western drywood termite soldiers have reddish brown heads.
Termites can range in size from 1/4 inch to 1 inch long, depending on the species, caste and maturity level. Workers are the smallest of the castes. Dampwood and drywood termites tend to be larger than subterranean termites.
SIGNS OF INFESTATION
The following list indicates common signs of a subterranean termite infestation. It is recommended that you have your house thoroughly inspected by a pest control professional trained to detect the sometimes subtle signs of termites. The following information is provided by the research of the National Pest Control Association:
The presence of mud-like material which lines the galleries in an irregular pattern.
Termites may excavate the wood so that only a very thin layer of wood is left on the surface between the cavity and the outside. Then this layer is broken, they will cover the holes with mud like material, used to make the tubes. This is a mixture of soil, feces, and saliva.
Swarmers: The appearance of a swarm of what you would call "flying ants",especially near light sources This indicates a nest may be near. A "swarm" is a group of adult male and female reproductives that leave their nest to establish a new colony. Swarming occurs when a colony reaches a certain size. Swarming is most common in the spring (March, April, May, and June) and occasionally autumn (September and October).
Most swarmers emerge during the day, most frequently on warm days after rain. Swarmers found outdoors near tree stumps, railroad ties, etc., are not an indication that your house is infested, but are present on the outside only. On the other hand, finding swarmers indoors often means that you have a termite infestation within your house. At first glance, swarmers and ants look similar, but can be distinguished by certain physical features. At Differences between ants and termites there is a picture and list of differences.
Mud Tunnels: Subterranean termites maintain their headquarters in the ground and build "mud tubes", pencil-size, that connect the nest (moisture) to the food source (wood).The tunnels may contain broken mud particles with fecal materials. Mud tubes or shelter tubes are proof of termite infestation, but their absence does not necessarily mean that a structure is free of termites. The insects may reach sills and other wood members through cracks or voids in the foundation wall, under the outside stucco, or from earth-filled porches, steps, terraces, or patios. You can break open tubes to determine if termites are still active inside. Termites often rebuild damaged tubes, another indication of continued activity. Old tubes are dry and will crumble easily.
Subterranean termites construct four types of tubes or tunnels. Working tubes (left) are constructed from nests in the soil to wooden structures; they may travel up concrete or stone foundations. Exploratory and migratory tubes (center) arise from the soil but do not connect to wood structures. Drop tubes (right) extend from wooden structures back to the soil.