Thrips deposit their eggs into plant tissue and the eggs hatch after 2-3 days, depending on the temperature and the plant host species (Figure 12). There are two feeding larval stages that are followed by two non-feeding pupal stages. The life cycle takes about 20-30 days from egg to adult, again depending on the temperature. Thrips disperse over long distances by wind. TSWV must be acquired by thrips during the larval stage of their development to be transmitted. Thus, only immature thrips that acquire TSWV, or adults derived from such immatures, transmit the virus. The ability of thrips to acquire TSWV decreases as the thrips age. Although the time in development that thrips can acquire the virus is limited, the wide host range for both virus and thrips facilitates development of epidemics. Once acquired by the larvae, the virus is passed transtadially, i.e. TSWV persists through insect molts from larval to adult stages. The virus replicates in thrips, and the thrips can transmit the virus during their entire life. There are at least ten species of thrips that transmit tospoviruses. Frankliniella occidentalis, the western flower thrips (WFT) (Figure 13), is considered to be the most important vector species because it is globally distributed and can transmit most tospoviruses.