What is the last part of the antennae known for being segmented and having an extra segment in drones?

The flagellum is the correct answer because it is the elongated, segmented part of the antennae in bees, which includes the most distal segments of the structure. In male drones, the flagellum is unique because it contains an additional segment compared to females. This extra segment can be a distinguishing characteristic of drones, aiding in the identification of the different types of bees.

The segmented nature of the flagellum contributes to the flexibility and sensory capabilities of the antenna, allowing bees to detect various environmental cues, such as pheromones and odors. The added segmentation in drones may also provide them with sensory advantages during mating flights.

In contrast, the scape is the basal segment of the antenna that connects to the head and does not have an extra segment. The pedicel is the second segment of the antenna, which supports the flagellum, but it is not involved in the differentiation of drones. The term antenna joint refers more generally to the connective points between segments rather than being a specific segment of the antenna itself.