ABSTRACT
Weather is the most important factor that determines the geographical distribution and periodic abundance of crop insect pests and parasites of an imals. Weather controls the development rate, survival, fitness, and level of activity of individual insects; the phenology, distribution, size, and continu ity of insect populations; migration and their establishment; and the initia tion of insect outbreaks (Pedgley, 1990; Drake and Farrow, 1988). Weather influence can be immediate, cumulative, direct, indirect, time lagged, ex ported, or imported. Indirect effects arise through host quality and parasite populations. A time-lagged influence is one that occurs at a later stage as a consequence of both past and current weather. Imported/exported influ ences arise because insects are highly mobile, and outbreaks may be initi ated by windborne migrations (Drake, 1994; Baker et al., 1990).