The Time Interval between Determination and Differentiation of Wings, Ocelli, and Wing Muscles in the Aphid Macrosiphum sanborni (Gillette)

Abstract

1. Approximately 10,000 chrysanthemum aphids (Macrosiphum sanborni) were raised in an investigation of the relationship of the time of determination of wings and related structures to the time of their visible differentiation. 2. Determination of wings takes place, on the average, three and three-quarter days before birth. 3. Differentiation of wings takes place approximately one day before birth, shortly after the initial pigmentation appears in the compound eyes. 4. About two and three-quarter days, therefore, elapse between determination and differentiation of wings. 5. Since ocelli and wing muscles are found only in winged forms, the determination of these structures is assumed to be fixed at the same time that wings are determined. 6. The average time of differentiation of ocelli is about two and one-half days after birth, and of wing muscles about one and three-quarter days after birth. If the assumption that these structures are determined at the same time as wings is correct, then a considerably longer time elapses between their determination and visible differentiation. 7. The action of a diffusible chemical substance is suggested as a possible interpretation of the relatively long time period between determination and differentiation of wings.