FEATURES OF A POPULATION OF THE FORMOSAN SUBTERRANEAN TERMITE, COPT0 TERMES FORMOSANUS, ESTABLISHED IN SOUTHERN CALIFORNIA

Abstract:
A population of the Formosan subterranean termite, Coptotermes formosanus Shiraki, detected in February 1992, was determined to be well established within a limited residential area of La Mesa, San Diego County, California, U.S.A. The large size of workers and soldiers, and annual swarms of reproductives in the La Mesa population (LMP) indicate at least one mature colony. The LMP have been found in soil, trees, and structures. Apparently introduced in wooden articles transported from Hawaii approximately 10 years ago, worker caste of the LMP have only been detected within 75 metres of the suspected point of introduction. No significant structural damage attributable to C. formosanus has been found. Less than 4% of 700 ground monitor stakes in the LMP area have reflected termite activity. Maximum activity at any ground trap has been 892 workers, and 13.9 g wood consumed per month, significantly less than reported for most other C. formosanus sites. In dye-release-recapture studies of the LMP, no dyed individuals released at a monitor site were recaptured, suggesting at least two possibilities: a.) foraging may be affected by population size or environmental stress, or b.) the LMP may be an exceptionally large population in which the relatively few released dyed termites were assimilated into a large number of foragers. La Mesa may be drier than is optimal for this species, and may retard the rapid spread of the LMP. Conventional termiticide is being used to protect structures while plans for eradicating the LMP are being developed.