The inherent ecological adaptiveness of fruit flies (Diptera: Tephritidae) ranks them among the worst invasive pest species, requiring vigilant detection, effective suppression, and regimented area-wide eradication. The US Department of Agriculture-Animal and Plant Health Inspection Service-Plant Protection and Quarantine (USDA-APHIS-PPQ) has a strategic goal to develop decision tools to prevent the entry and spread of quarantine-significant fruit flies posing threats to the health of US agriculture and natural resources. To achieve this strategic goal, USDA-APHIS-PPQ developed the Compendium of Fruit Fly Host Information (in short, CoFFHI: https://coffhi.cphst.org/), an interactive application integrating verified records of fruit fly infestations on their documented host plants, worldwide. Pertinent publications and manuscripts were acquired through the use of searchable online databases. Infestation data retrieved from the literature were classified as providing field infestation data, laboratory infestation data, interception data, or a mere listing of a fruit or vegetable as a host without providing any verifiable infestation data (i.e., listing only data). The taxonomy of recorded host plants was verified using the USDA-Agricultural Research Service (ARS) Germplasm Repository Information Network (GRIN, https://www.ars-grin.gov/) and other 364taxonomic resources. CoFFHI, Edition 4.0 has four integral components: (1) comprehensive fruit fly species-specific host plant databases of 24 select quarantine-significant fruit fly pests of horticultural commodities; (2) provisional host lists for the same 24 select fruit fly pests; (3) the Tephritidae Databases, which comprise name, host plant, and distribution data for all fruit fly species; and (4) infestation records of the Dacinae of the Pacific Islands. CoFFHI, Edition 4.0 is a vital USDA decision tool in achieving the core mission of APHIS-PPQ in preventing the introduction and establishment of exotic fruit flies into the United States and in facilitating safe domestic and international agricultural trade.