Abstract
The salivary gland chromosomes of 263 larvae of D. immigrans obtained from several natural populations in southern-central districts of Japan were examined. Three different types of heterozygous inversions occurring in the second chromosome were observed, and the mean frequency per larva was 0.19. These inversions seemed to be similar to those reported by Freire-Maia and Brncic in natural populations in Brazil and Chile. This species would be sensitive to certain climatic conditions because of its poor chromosomal polymorphism.
The variation in number of collected flies was also observed in relation to seasonal changes and the elevation.
