Termite Distribution


Zootermopsis angusticollis is confined to western North states. It abounds from British Columbia south to the Mexican border. It has a wide altitudinal range, being found usually in the more humid coastal areas, but at times in the south occurring as high as 6,000 feet. Halo terries minor like the damp-wood termite is confined to western North America, being most common in California, Arizona, and New Mexico. It is the most destructive of the American species of wood-dwelling termites. It is the most common along the coast from northern California southward to Mexico with scattered stations as far north as Tacoma, Washington and as far east as Arizona.
Termites found in the open woodlands of the Pacific Coast area others are spread out in widely different areas throughout the United States however, as are species of the other two groups.

Climatic factors in distribution

First. the effect of moisture the most important factors is an available supply of moisture. Without the latter no colony can long exist. Termites lose water rapidly, especially in their larval stages, due to evaporation. An approximately saturated atmosphere can be maintained in their closed burrows, and they appear to be very sensitive to even minute changes in humidity. In general, termites obtain their supply of water from three sources, namely: the soil, wood, and metabolism. In the subterranean species, humidity is maintained within the colony by a diffusion of moisture in the soil. These termites prefer sandy soil as a more favorable environment for locating and attacking buried wood. It has been found that the elevation of infestation in a tree is directly proportional to the supply of moisture. Thus at high altitude in some parts of California where moisture is very abundant, the attacks by the subterranean termites may even reach at times to the tops of telegraph poles. The damp-wood termite, as the name implies, requires more moisture than the dry-wood species. Hence it abounds in such habitats as rotting logs, staves of water tanks and pipe lines, bridge piling, harbor structures near and over the sea. Even dry-wood termites are attracted where a plentiful, supply of moisture is at hand. However, the fact that the dry-wood species are able to maintain a relatively high humidity in their burrows with just a small supply of moisture makes it possible for them to invade trees. They are able to advance into new localities only as long as their water supply lasts. When it fails them they either retreat downward toward the supply, or if it fails them completely, they die.

Second, the effect of temperature. Temperature as well as moisture is an important factor in the behavior of insects. Colonies of subterranean species in buildings often make burrows about warm rooms, near steam pipes and the like. Their tunnels are placed on warmed surfaces or toward the sources of warmth. In desert regions where the temperature is known to fluctuate rapidly and markedly, termites shift the location of burrows accordingly to avoid exposure to the cold or to the sun. Winter slows down the activities of termites and drives them downward, while summer hastens their activities and brings them upward.

Geographical occurrence also is influenced and determined by maximum and minimum limits of temperature. Thus Zootermopsis angusticollis might be subjected to low ranges of temperature
a little farther south, termites of the same genus and species are found in fairly high temperature conditions. Keticulitermes is the only genus that really extends into temperate regions. Lalotermes minor occurs usually in warm and sheltered regions; but as it enters the heated desert, it descends below the surface if the ground becomes too hot.

Together, moisture and temperature may act in diametrically supposed ways on different species in the same locality at the same time. Thus a certain degree of heat and moisture might be adequate for one species e. g. halotermes minor. But this species will be checked from spreading by a lower temperature in the new territory — for example, the coastal belt, while another species such as Reticulitermes flavipes does not enter the desert region because of the lower humidity there.

On the other hand, Reticulitermes flavipes requires both a high temperature and high humidity for its dispersal flight. Thus this species emerges on sunny afternoons just after a heavy rain which has lasted till late in the afternoon. Xaloternes has its dispersal flight mostly on days after a sudden rise in temperature when the humidity is low and there has been no rain preceding. Both however, have their dispersal flight during the most brilliant sunshine. Zootermopsis has its dispersal flight in the same locality in late afternoon or evening when the temperature is falling and the humidity is rising.

Because of the protection their nests afford, termites are more or less immune to cold although most activity ceases during the winter months.