Although elevated levels of carbon dioxide have been used in controlled atmosphere treatments with low oxygen levels for a number of deciduous crops, the use of much higher concentrations of carbon dioxide followed by a short cold treatment for citrus was only suggested as a viable option for disinfestation in 2005. Carbon dioxide alone, for a period of 24 h at concentrations up to 70% in air caused variable levels of mortality of Thaumatotibia leucotreta (Meyrick) larvae in citrus, but never completely controlled this pest. The susceptibility to carbon dioxide appeared to vary more with the batch of T. leucotreta eggs than with different citrus cultivars. By following CO₂ fumigation with a short cold treatment, complete control of this pest was achieved and the results with sequential treatments were more consistent. The efficacy of the combined treatment was reduced when it took ≥12 h to move fruit after fumigation into a cold room at 2°C, or if the temperature was not reduced below 12°C within 24 h after fumigation. In these cases, the benefit of the short cold treatment was lost and mortality was similar to CO₂ fumigation alone. These results hold promise for the development of a shorter commercial treatment to meet quarantine restrictions against this pest in citrus.