Answer:
The answer to your question is because of surface tension
Explanation:
Surface tension is defined as the property of the surface of a liquid that allows it to resists an external force.
From the definition, we conclude that the molecules at the surface of water are extremely close and do not allow certain bugs to penetrate it so they can walk through it.
While the molecules at the surface of octane are not as close as those molecules in water so a bug sinks on it.
In conclusion, the surface tension of water is higher than the surface tension in octane.