Many Liriomyza species are pests of agricultural and ornamental plants. In the past two decades, the occurrence and distribution of certain Liriomyza species have changed dramatically, leading to an extensive body of research papers. First, we review the association of thermal tolerance with population dynamics, geographic distribution, and species displacement. Differences in thermal tolerances between species result in their differential geographic locations and overwintering ranges. Displacements among Liriomyza species are associated with their temperature adaptation. We examine the chemical linkage of plants, Liriomyza, and their parasitoids. Chemical compounds from host and nonhost plants mediate the behavior of Liriomyza and their parasitoids. Liriomyza and their parasitoids use chemical cues to locate their hosts. Induced compounds can be used as attractants of parasitoids or repellents of Liriomyza. Thus, understanding the thermal tolerances and chemical ecology of Liriomyza may enable researchers to predict geographic distribution and to develop novel control strategies.