During investigations on the economic position of Collembola a significant attack on mangolds by one species of this group occurred at Rothamsted in the classical mangold field known as Barn Field. The particular species involved was Bourletiella hortensis, Fitch (pruinosus, Tullb.). Although the economic position of Collembola has not, as yet, been fully established, this member of the order can claim priority in the list of previously reported economic species. The first British record of injury probably by this species is that of Miss Ormerod in 1894, when she reported leaf damage to turnips in Scotland. Since then British records include as host-plants sweet peas, beans, radishes, lettuce, mangolds and soy beans. Reports from America confirm the economic position of this species, and in Canada Macnamara states “ the list of plants it is known to injure reads like an index to a seedsman's catalogue : beans, beet, cabbage, cantaloupes, carrots, clover, corn, cucumber, kale, lettuce, mangolds, onions, peas, potatoes, radishes, rye, spinach, squash, tobacco, tomatoes, turnips, violets, watermelons, wheat, wild cucumber.”