Brazilian peppertree (Schinus terebinthifolia Raddi), a native South American tree, has invaded disturbed sites and natural areas in peninsular Florida. We report Brazilian peppertree as a new host for a little-known heteropteran, the Neotropical scutellerid, Tetyra antillarum (Kirkaldy), whose U.S. distribution is restricted to Florida. In 2016 to 2019 and 2021, we collected a total of 10 nymphs (all instars except IV) and 56 adults by beating fruit-laden branches in mid-February, early March, and early April. Multiple introductions of Brazilian peppertree in south Florida and eventual intraspecific hybridization of two haplotypes (Miami area and Gulf Coast) created genotypes more suited to Florida's climate, which fueled aggressive northward expansion in the peninsula. We review the history of Brazilian peppertree's planting in Florida and its northward expansion in the interior of the peninsula. As a corollary, we propose that Brazilian peppertree's northern spread in the peninsula triggered subsequent range expansion by T. antillarum. Our supposition is based on fruit of the novel host being available in fall and winter when fruits of most other woody plants are lacking, coupled with absence of the bug's other known host, gumbo limbo (Bursera simaruba [L.] Sarg.); this tropical tree is not hardy in the Lake Wales Ridge where T. antillarum was most numerous. First collected at Key West in 1887, the scutellerid now is known from the peninsula's northeasternmost county, Nassau, which borders on Georgia. We present new records of T. antillarum from Florida and countries in Central America and the West Indies, and new state records for Mexico. Certain U.S records of T. antillarum posted on the internet are referred to T. bipunctata (Herrich-Schaeffer).