These Bloon invasion events can be annoying for players with many tiles captured, especially for those with over 1000, 2000, or even all 3000 captured. Tired of scrolling all around your city to find these little blue spies? Here's the solution.

First, a few basics:
The max # of blue spies you can have at once is 10. 1 spy takes about 20 minutes to spawn
The spy spawn locations may seem randomly scattered around your city, but it is not entirely random.

The spies prefer to spawn where your monkey actors are. This means that any building that spawns a monkey (pretty much every Monkey Building, as well as a few MvM buildings & Banana Farm), or where your decoration Monkeys are placed.

Even if there are no monkeys visible with no paths placed, valid spy spawn areas will be around the buildings and where monkey decorations are placed. This means that both buildings and monkey decor placements influence where spies spawn.

On smaller cities with few tiles captured, this wont really matter as finding the spies will be easy. This will only help on larger cities with more buildings.
For the blue event spies, it appears they prefer to spawn in more densely populated areas if they can, meaning you should see more spies in 1 spot if you were to place tons of monkeys on that spot.
If they do spawn near buildings anyway, you can easily refresh the game to make them spawn in the one spot.

Red spies are trickier as refreshing isn't as fast so it would be easier to just go and look for them anyway.

Once I popped the 5 spies, I simply refreshed the game (minimizing the window works) then popped the other 5 that spawned there. No more having to look around for them and struggle to find them.
Sometimes they don't cooperate and can require a few refreshes, but it beats looking around the entire city.

This can also really help if you haven't been paying attention to the time / lost count of how many spies you popped.