Where do Water Boatmen come from

[pen]

Excuse my ignorance.
When a garden pond starts off clean, how do water boatmen initially get there?

[dilf]

its amazing how life will manage to overcome the odds .for instance shell craters in ww1 were often flooded and found to contain eels [which can travel overland when necessary] or fish colonise landlocked ponds [some say it can only be eggs on ducks feet]
water boatmen are insect like so probably were either blown there as eggs or hitched a ride on another creature.

[hammerman]

I do believe they have wings !!!!!.....'orrible creatures