The genetic diversity and population genetics of the citrus mealybug, Planococcus citri Risso, 1813 (Hemiptera: Pseudococcidae), were investigated based on sequencing of mitochondrial DNA. A total of 108 individuals were collected from different host plants in Turkey during 2011-2015. Partial sequences of the cytochrome c oxidase subunit 1 gene revealed five haplotypes in Turkey, with one of these (Hap 1) as the common haplotype, being present in 102 individuals. Additionally, 90 homologous nucleotide sequences retrieved from GenBank were incorporated into the analyses and compared with sequences of isolates from Turkey. Molecular diversity indices revealed overall high mitochondrial DNA diversity for these populations. Further, Tajima's D test and Fu's Fs test showed negative values, except in South Africa, indicating deviations from neutrality and suggesting recent population expansion for the populations. Pairwise comparisons of the different populations using the pairwise fixation indext was significant for some comparisons, indicating genetic differentiation among the P. citri populations studied. Based on these findings and those from earlier studies, it was hypothesized that demographic expansion has occurred in P. citri via the introduction of mealybugs by anthropogenic movements.