In October 1921, when banding fruit trees for Anthonomus pomorum, L., numbers of larvae of Boriomyia nervosa, Fab., were found spinning up in the bands. The numbers were such as to attract attention, and afforded an excellent opportunity for working out the life-history.

The cocoons were rather coarsely made, very loose, and in the mesh could be seen numerous oil-like globules. The larvae lay in a characteristic curved position in the cocoons with the head bent forward until it rested on the underside of the thoracic segments, the legs being slightly folded inwards. They remained quiescent in the cocoons until the spring of 1922, when many specimens pupated in March.