This paper estimates original yields for five grains in thirty-three provinces of Spain in the mid-18th century. We observe a strong heterogeneity between the provinces with yields being considerably higher in the north of the country than in the south-east. Although average yields in Spain were below those in other countries of north-western Europe, the provinces in the north achieved yields not far behind the most advanced agricultural regions of the world. The heterogeneity of yields across Spain can be explained by the different climatic conditions in each province. Although all the provinces improved their yields in the long term, the differences between the provinces remained stable until the modernisation of Spanish agriculture around the mid-20th century.

This paper describes briefly four different locust species that constitute potential widespread danger to agriculture and pasture in the eastern, central and southern Africa region. Particular reference is made to the red locust, Nomadacris septemfasciata Serville which mostly feeds on monocotyledonous plants. Reference is also made to the African migratory locust, Locusta migratoria migratorioides R&F; the brown locust, Locustana pardalina Walker; and the desert locust, Schistocerca gregaria Forskal. There were frequent reports of damage to cereal crops by the red locust during the most recent plague of the 1930's. However, since that time only a few yield loss data are available owing, primarily, to the fact that locust infestations have mostly been irregular and confined within their natural breeding areas, away from crop land. The paper provides general background information that should enable evaluation of locust incidence in the region and assessment of consequent cereal crop production losses.