Isoptera: Rhinotermitidae: Reticulitermes hesperus Banks, 1920 (Western Subterranean Termite)

On warm sunny days following the first autumn rains, swarms of the winged adult forms of this termite are commonly noticed emerging from frame houses, fence posts, and other wooden structures that touch soil. The species has a high humidity requrement, which forces it to maintain contact with the ground, travelling up and down between its subterranean galleries and the wood through protected cracks in mortar or concrete foundations, or through earthen tubes that it constructs from soil, saliva, and chewed bits of wood.

Photograph by C. Hogue

In Los Angeles and much of the west, this is the species that causes the greatest damage. It is probably safe to say that the majority of older houses in the Los Angeles area are infested to some degree with this termite. In general, however, damage is not noticeable until tunneling activity has proceeded to the point of weakening structural members in stressed areas, such as flooring and stairways. Severe damage requires a period of years to develop: our termites do not reduce a house to a pile of sawdust overnight! Homeowners are urged to have periodic inspections to determine the presence of termites. This is simply good insurance and should be done regardless of how many preventative methods were employed in the original construction.

This species is distinguished from others that are prevalent in the basin by the black heads of its sexual forms, its earthen tubes, and the fact that it does not make pellet piles. Its tunneling pattern is also different: the workers attack wood only in the soft spring growth region of the annual rings. Thus a cross-section of an infested timber shows a characteristic pattern of concentric circles or arcs.

© 1993 Insects of the Los Angeles Basin