Outbreaks of the African armyworm, Spodoptera exempta (Walker), in East Africa follow a seasonal pattern related to the movement of the inter-tropical convergence zone. The season typically begins in central Tanzania with primary outbreaks that coincide with the arrival of the rains. An analysis of 27 years' light trap records shows a high negative correlation between the total number of moths caught by light traps during the season over the whole country and the number of rain days during November in central Tanzania. Out of the 27 seasons, 22 could have been correctly predicted as 'light' or 'severe', using the November rainfall at one station, Dodoma, in time to give two months' warning before the peak of the season.

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Many development interventions have failed to generate the desired impact among African resource-poor farmers for reasons including the centralised and top-down approach, lack of active community participation, and overreliance on external information and technology delivery strategies and channels. The migrant African armyworm, Spodoptera exempta, is among the major challenges threatening livelihoods of millions of farmers in East and Southern Africa. Outbreaks occur suddenly and can devastate crops and pasture. National and regional forecasting services have been operational since the 1960s to provide warning of potential outbreaks. This system relies on information from armyworm moth traps usually operated at district level. These centralised services have a number of difficulties and limitations which include: delays in communicating trap catch data to the forecaster; forecasts are not village specific; forecasts do not reach many farmers; lack of responsibility and local ownership of traps. An innovative approach called community-based armyworm forecasting (CBAF) was developed as a response to these limitations. The new approach has been piloted and tested in several East African countries and found to be effective. CBAF establishes a system that allows each village to have its own traps and trained forecasters who collect and interpret data, and provide village specific forecasts. A recent project on CBAF piloted the approach in 10, 5 and 39 villages of Malawi, Zimbabwe and Tanzania, respectively, in the 1 st year, and in a further 25 and 38 villages of Malawi and Tanzania in the 2 nd year. Discussion with stakeholders, field observations and assessments conducted by the authors indicate that the initiative has generated a number of benefits. It built local capacity, and because of the location specific early warning it enabled farmers to combat the pest more effectively. It was noticed by the authors that local communication channels and folk media play an important role in CBAF, complementing and enhancing the effectiveness of exogenous channels. This paper discusses how CBAF makes effective use of different communication channels and capabilities, and highlights preliminary results.