The development of a male bee (drone) takes how long?

The correct answer is 24 days.

In a honeybee colony, the developmental timeline of a bee depends on its caste (queen, worker, or drone). Drones are male honeybees, and they have the longest development period among the three castes.
The total development time of 24 days is divided into three distinct stages after the egg is laid:

1. Egg Stage (3 days): Like all honeybees, a drone spends its first 3 days as an egg.

2. Larval Stage (6.5 days): The egg hatches into a larva. During this stage, it is fed copiously by nurse bees. The larval stage for a drone lasts approximately 6.5 days.

3. Pupal Stage (14.5 days): After the larval cell is capped with wax, the larva spins a cocoon and begins its transformation into an adult bee. This pupal stage takes about 14.5 days for a drone.

Adding these stages together:
$3+6.5+14.5=24$ days.
Therefore, it takes exactly 24 days for a male bee (drone) to develop from an egg into an adult.