Webs constructed by African armyworms, Lake Manyara National Park, Tanzania

The African armyworm is not actually a worm at all but rather the larval (caterpillar) stage of the night flying moth, Spodoptera exempta. The normal seasonal cycle of the armyworm begins with low-density breeding in the cool, coastal highland of Kenya and Tanzania. These small populations of the "solitary" phase do little or no crop damage but as the Inter Tropical Convergence Zone begins moving northward the strong winds carry the moths into the interior highlands where the initial outbreaks can occur. It is in these highland areas that a peculiar and not well-understood biological mechanism may occur whereby the solitary pest transforms into the 40 times more active gregarious form. The voracious appetite of this gregarious form is such that a heavy infestation can consume rangeland grasses or wheat, barley, teff, maize, sorghum or finger miller faster than 400 head of cattle per hectare and vast areas can be decimated overnight. This photograph was taken when Eliot Elisofon was on assignment for American Broadcasting Company and traveled to Africa from June 1966 to early August 1966.