These three preparatory drawings are for a series of engravings known as ‘Vermis Sericus’ (‘The Silkworm’), a history of the silkworm and silk-spinning by Karel de Malle, published by Philip Galle. In the centre silkworm cocoons are seen floating in warm baths before the threads are unravelled and wound round winders. In the distance cocoons are laid out to dry in the sun.