 The worms never sleep and they won't eat dried leaves, so we have to get up early to feed them and don't go to bed until late. It's a lot of work, Bibi Khan explains in a hushed voice as she gently places leafy branches onto the remains of existing ones. Bibi Khan is a tired mother of three who lives with her mother-in-law in a village just outside Khiva in Uzbekistan. She'll spend the summer working her cotton and wheat fields whilst her husband is off in Moscow working as a migrant labourer.