Answer:
The momentum of an object is equal to its mass multiplied by its velocity. So, even though a bug typically has much less mass than an airplane, if it is moving at a high velocity its momentum will be greater than the airplane at rest.
This is because momentum is a measure of an object's "inertia," or its resistance to changes in motion. An object with a high velocity has a greater tendency to keep moving in the same direction, whereas an object at rest has no velocity and therefore no tendency to move.
So, even though the airplane has a much greater mass than the bug, the bug's high velocity gives it a greater momentum.