Laboratory studies and field observations were conducted to ascertain the development of the female sex organs of the alfalfa weevil during aestivation, to study the role of this aestivation on sexual development, and to investigate the factors responsible for this interaction.

Measurements of female sex organs were made in dissected weevils at monthly intervals to observe each of the developmental stages of sexual maturation. Results of this sexual development as it progressed after adult emergence, were presented by means of tables, graphs, and a series of photographs.

The importance of not confusing old and new weevils was recognized in this work, since their behavioral patters differ in many respects. The nature and physiology of the aestivation of this weevil was discussed and evidence was presented to support the author's suggestion that this aestivation is a "true diapause." It was demonstrated in this paper that diapause synchronized the sexual growth of the alfalfa weevil to the seasonal changes of the year for species adaptation and survival.