Timbuktu or to study. By 1300, the population increased to 10,000 and kept increasing until it reached about 50,000 in the 1500s. There is insufficient rainfall in the Timbuktu region for purely rain-fed agriculture and crops are therefore irrigated using water from the River Niger. The main agricultural crop is rice. African floating rice ("Oryza glaberrima") has traditionally been grown in regions near the river that are inundated during the annual flood. Seed is sown at the beginning of the rainy season (June–July) so that when the flood water arrives plants are already in height. The plants grow up to in
Elasmopalpus brown anterior and distal margins. The larvae feed on a wide range of plants but prefer grasses. Recorded host plants include a number of economically important plants such as "Phaseolus vulgaris", "Beta vulgaris", "Brassica oleracea" var. "capitata", "Cucumis melo", "Cyperus esculentus", "Zea mays", "Vigna unguiculata", "Phaseolus lunatus", "Avena sativa", "Pisum sativum", "Arachis hypogaea", "Capsicum annuum", "Oryza sativa", "Secale cereale", "Sorghum bicolor", "Glycine max", "Sorghum sudanense", "Saccharum officinarum", "Ipomoea batatas", "Lycopersicon esculentum", "Brassica rapa" and "Triticum aestivum". They tunnel into the crown of their host plant, severely weakening large plants and often killing young seedlings. They spin silken tubes near the