A species of tent caterpillar which occurs in the prairie region of Canada, from southern Manitoba west to the foot-hills of Alberta, and which often occurs as a pest on rose, cherry, and gooseberry has been referred to as Malacosoma fragilis (Stretch) (properly fragile). In 1881, Stretch described fragile from Virginia City, Nevada, and an examination of Stretch's type in the American Museum of Natural History showed that this species possesses a grey ground colour and in this respect is quite unlike the fawn-coloured species from the Canadian prairie.