There is a certain locust that is eaten in the southern Africa region and provides a scrumptious meal similar to termites. Because locusts are smaller than other meat types (hares for instance) and do not congregate in one place in the same manner as termites, they are a bit more difficult to catch. However in the early hours of the morning the locusts will be stiff from the cold and will find it harder to fly away. Hence the early risers take advantage of this and the late risers will find the locusts either taken by others or trickier to catch. This is how our elders taught us the importance of acting early or else we will find the opportunities taken or diminished.
The proverb is used to encourage early action in going about any project or task. It can also be used to explain the advantages that people have had in life over others.