“…Flies in the family Cecidomyiidae are typically minute in size, and many species form galls on host plants (Merritt et al 2009). Several species, notably Hessian fly, Mayetiola destructor (Say) and swede midge, Contarinia nasturtii (Kieffer), are specialist herbivores and serious agricultural pests (Hallett & Heal, 2001;Lamiri et al, 2001;Liu, Mori, et al, 2019;Liu, Chen, et al, 2019;Schmid et al, 2018), while others, such as the aphid midge, Aphidoletes aphidimyza (Rondani), and leafy spurge gall midge, Spurgia capitigena (Bremi), have been studied for their potential as biocontrol agents (Boulanger et al, 2018;Lloyd et al, 2005). There have been several population-level studies of cecidomyiids (for instance, Skuhrava et al, 1984;Black et al, 1990;Lloyd et al, 2005;Redfern & Hunter, 2005;Sato et al 2020); however, population genetic assessments have typically been limited to only a few molecular markers (e.g., allozymes or gene sequences).…”