You can drown some bugs.
However not all bugs will drown when you try to drown them.
Also in reality most bugs actually suffocate rather than actually drown when they die of a drowning.
Not all insects drown in water.
In fact, quite a few live there for at least part of their lives.
Insects breathe through holes in the sides of their bodies.
If they can't get air in through the holes, they will suffocate.
And most insects can survive under water (or in saturated soils) for short duration's.
In some ways, insects breathe like us and in other ways, insects breathe in a completely different way.
If humans don't receive oxygen, they can die within a few minutes, but almost all insects can survive without oxygen for many hours.
Insects have tiny brains inside their heads.
They also have little brains known as “ganglia” spread out across their bodies.
The insects can see, smell, and sense things quicker than us.
Their brains help them feed and sense danger faster, which makes them incredibly hard to kill sometimes.