Probably true! Ants just LOVE to tunnel through nice dry sand. I have seen them do a job on patios. It's recommended to use polymeric sand on the top to fill the spaces, because polymeric sand hardens up with water and ants can't tunnel through it. Another option is to use stone dust instead of sand.

The sand I use between pavers here in PA is called polymeric sand (contains polymers). It sounds like the same thing as stabilizing sand mentioned above. It is costly. It is around $22.00 for 60 pound bag. It comes in a tan or gray mixture. I don't suppose there is much limestone available in Florida. We use a base of modified stone here (limestone about an inch or so mixed with limestone "dirt" (that's the modified part), so that you can put down a 4 - 6 inch base and tamp it so that it really packs down. Then use 1 inch diameter pipes (appropriate length(s)) to lay down on the packed base which is slightly sloped for water runoff, dump sand (coarse construction or cement sand) in the area of the pipes that are resting on the base and use a straight board (2 x 4) of required length to "screed" or level the sand (don't tamp it) to the one inch depth (the top surface of the pipes will be slightly exposed). Starting at a convenient spot, lay the pavers on the sand and work your way around the area, moving the pipe as required to cover a manageable section with sand, laying pavers as you go. Try to slide the pipe(s), maintaining contact with the base at all times, and fill in the groove left by the pipes with sand, leveling lightly with a flat metal cement hand trowel or something similar.

Sure you can do it! If you are meaning true flagstone vs. pavers, the pavers will be infinitely easier because they are uniform in size and smooth. I've seen some "flagstone look" concrete pavers which would be pretty much the same as the brick style - I believe the flagstones have a half-dozen or so shapes which interlock giving the irregular look. I built our paver patio having never done anything like it before. It just takes time, a wheelborrow, muscles and sunblock. Doing it yourself, you won't have the rest of the lawn torn up with equipment. A landscaper once told me he counted on lawn repair following a patio install. Here are some photos of ours - information is below some of the pictures. Good luck. Here is a link that might be useful: Patio

Being a professional landscaper as well as living in the PNW, your best options are using either more of 1/4" minus or sand to fill the gaps or soil with moss or groundcovers. The 1/4" probably offers the best permeability. It does compact very satisfactorily so should not be a concern migrating endlessly across the flagstone. I have seen all three methods work equally well.......it is just a matter of what you prefer and what you consider to be the easiest solution. ETA: hopefully you also factored in an appropriate slope (1-2% or a 1/2" fall over a span of 4') to the patio construction. That is very necessary and should satisfactorily address any pooling of water issues.