Mitochondrial DNA (mtDNA) was employed to investigate inter- and intraspecific genetic diversity within the Lygus genus. The main emphasis was on L. lineolaris because it is a widely dispersed species occurring in many regions of North America. Part of the mtDNA cox1 and cox2 gene regions were used to ascertain maternal lineages among prevalent Lygus species. A 768 bp region overlapping those two genes was amplified and sequenced in L. lineolaris individuals originating from the Red River Valley, the Gulf Coast, New England, and eastern Canada. Specimens collected from North Dakota, Minnesota, Vermont, Quebec, Alberta, and Ontario identified as L. lineolaris showed similar sequence patterns. Most individuals fell into two closely related clades; however, a few individuals from Arizona, Mississippi, Michigan, and Connecticut were found to be distinctly divergent and fall outside of the two primary L. lineolaris clades. Genetic variation within regional populations and between widely dispersed North American sites is similar indicating a lack of geographically based population structure. Other important species of Lygus (L. hesperus, L. keltoni, L. borealis, L. elisus, L. shulli, L. plagiatus, and L. rugulipennis etc.) were collected from different geographic locations and they are being evaluated to assess genetic divergence within this genus. The non-L. lineolaris species are distinct from the two L. lineolaris clades. However there is an apparent discordance between the observed gene tree and the anticipated species tree in that the non-L. lineolaris species do not appear to form monophyletic groups. The reason for this is under investigation.