The development of insects that live within plant tissues has always been difficult to observe. Reliable information on their biology has been obtained by making daily dissections of infested plants but that procedure sacrifices both insects and plants and does not allow continuous observations of individual insects from plant entrance to emergence. Milner et al. (1950) developed an X-ray technique which provided satisfactory delineation of internal infestation of insects in grain. With their method they were able to observe insect development of the granary weevil, Sitophilus granarius (L.), and the rice weevil, Sitophilus oryzae (L.), without any deleterious effects of radiation upon their development. Other techniques applied in seed testing (Metzner 1962), coffee beans, and nut evaluations (Esteves 1959; Vilar 1966) are not applicable to soft vegetable materials such as maize stalk and ear.

It is often necessary in queen quality, package bee development, and wintering studies to locate the queen at different times to determine her presence, weight, location, etc. In the spring, colonies are small and locating the queen is not difficult. However, in late summer, when colonies reach up to 60,000 worker bees in five or six supers, the task becomes very difficult and time consuming. While the use of radioactive tags as a means of following the movement of insects has been well established (Amason et al. 1950: Green et al. 1957; Gomez et al. 1962; Baldwin and Cowper 1969), their use for studying the movement of bees has been limited. Radioactive paint was used by G. A. Tomes (1940) and Raudszuz (1958) for marking queens but apparently proved unsuitable. This study was conducted to determine the possibility of using platinum-iridium (IR-192) tags as a means for rapid, repeated recovery of queens during the producing season