Vapor heat treatments were developed against life stages of the mealybug Maconellicoccus hirsutus (Green) (Homoptera: Pseudococcidae). Treatments tested were 47°C for 5–50 min in 5-min increments and 49°C for 3, 5, 8, 10, and 12 min. All tests were conducted with mixed age M. hirsutus on Chinese pea, Pisum sativum L. Treatment at 47°C required 45 min to kill all M. hirsutus, whereas treatment at 49°C required 10 min. The adult female and nymphal stages were the most heat tolerant at 47°C, but the egg stage was the most heat tolerant at 49°C. Use of the vapor heat treatments on other commodities will require achieving or exceeding the proper temperature and duration at all locations on the host where M. hirsutus may reside.