A total of 797 specimens of wild adult triatomines, belonging to six species from the entomological
collections of the Costa Rican National Biodiversity Institute, was studied from the standpoint of their relative abundance, as reflected by light traps, distribution in the country, seasonal variations and climatic and altitudinal preferences.
Triatoma dimidiata was the most abundant species (32.9% of the total specimens), with a very extensive
distribution in different ecological zones, being more common between 100 to 400 m above sea level mainly
at the end of the dry season. T. dispar was the third in frequency (21.5%), with narrower distribution, more abundant between 600 to 800 m and scarce during the dry season. Panstrongylus geniculatus and P.
rufotuberculatus, second and fourth in frequency (22.1% and 15.1%, respectively), were widely distributed on both the Pacific and Caribbean basins, the former being more common between 80 to 270 m all year round
and the latter below 800 m mainly during the first semester. Eratyrus cuspidatus which represented only 4.9% of the insects, was also present on both basins mainly below 200 m with a tendency to be scarce during
certain months of the year, and was found in all types of ecological zones. Finally, Rhodnius pallescens, the least abundant species (3.6%) was restricted to very humid areas below 20 m, on the north side and
Caribbean basin. With the exception of R. pallescens, males were more commonly found than females.
Some epidemiological implications related to the six species are discussed.