The karyotype and chromosome behavior of C. capitata were studied both in mitosis and meiosis. The chromosome number is 12 (n=6), and includes two pairs of metacentric chromosomes, two pairs of submetacentric and two pairs of subtelocentric chromosomes. The sex chromosomes are well differentiated in size, and the X chromosome is typified by a secondary constriction. The somatic chromosomes display somatic association, which can be relaxed by colchicine. Spermatogenesis is typically chiasmatic, suggesting that recombination occurs in the male. The study was supported in part by the Israel National Council for Research and Development.