This paper explores the relationship of weeds and crop parasites in the domestication of crop-plants within the Old World, drawing predominately on China and the Near East. This relationship is explored using the concept of niche construction in which the act of cultivation sets about chains of feedback in which the ecological worlds of plants and humans became increasingly intertwined resulting in ever increasing spheres of interdependence. Into this domestication entanglement a number of peripheral organisms (termed parasitic domesticoids) were drawn, from the weeds which came to inhabit arable fields, to the insect pests and rodents that came to settle in the grain stores of the first farmers. The evolution and spread of these organisms is then outlined against that of the crop itself.