From the duration of larval stages and the transport velocities of surface drift bottles conclusions are drawn relating to the origin of larvae of two species of stomatopods found off Den Helden in the southern North Sea. It is probable that, besides the English Channel, the area of distribution of propagating Squilla desmaresti includes the southern part of the North Sea. It is certain the Heterosquilla eusebia produces larvae within the southern North Sea; it is uncertain whether Dutch waters also receive larvae from the Channel area.