Alstad, D.N., & Edmunds, G.F. 1983 Selection, outbreeding depression, and the sex ratio of scale insects.. Science 220: 93-95.

Notes: Abstract: Nuculaspis californica, the black pineleaf scale insect has haploid males and diploid females; ratios of males to females late in development ranged from 0.005 to 0.320 among insect subpopulations that were infesting different host trees; demes well adapted to an individual ponderosa pine had a higher proportion of males than did demes that were poorly adapted to the host; ratios of males to females rose in successive annual samples as natural selection increased insect adaptation; gene flow between demes on different host trees produced predictable changes in the sex ratio. Keywords: males.