Experimental interspecific hybridization between the notorious, worldwide horticultural crop pests Liriomyza trifolii (Burgess) and Liriomyza sativae Blanchard is reported. Premating reproductive isolation was easily disrupted under no-choice crossing conditions; hybrid flies were obtained only in one mating combination (female L. sativae × male L. trifolii). Crosses between them yielded only female progeny, which had some superficial characters identified as L. sativae, but the shape of the genitalia was similar to that of L. trifolii. All of the F1 hybrids were sterile and could not be backcrossed to either parental species. An electrophoretic analysis of internal transcribed spacer region sequences on ribosomal DNA genes and a nucleotide sequence analysis of mitochondrial DNA cytochrome oxidase subunit I DNA sequences confirmed that the progeny were not the result of parthenogenetic reproduction.