Vapor heat treatment (VHT) was adopted as a quarantine measure in 1992 when Mediterranean fruit fly invaded into the State of Florida. As a quarantine safeguard to prevent its spread, all fresh fruits shipped from Florida to other States were treated with vapor heat, VHT emerged in Japanese plant quarantine in 1969 when it was approved as a key condition for lifting import ban on fresh fruits of papaya from Hawaii. The treatment standard for Hawaiian papaya was drawn by USDA-APHIS on the basis of a series of experiments.