I'm trying to find a quick system to detect when a zergling unburrows.

My previous test involved using a dropship. Whenever the dropship unloaded a marine the marine was reloaded and a burrowed zergling was created underneath. I then created a cloaked wraith over the zergling that could kill it in one shot after it saw it. However, it took at least half of a second for the wraith to take a shot after the zergling unburrowed, which is too slow. And i do not like the look of the zergling's death.

I know that i could fine tune this system more but i would like a more accurate way to detect when a zergling unburrows.

One method I can currently think of is having a DT or another unit be constantly moved to a 1x1 location following the ling. If the DT is in the 1x1 location, the zergling would be burrowed. If the DT is not in the location, then the zergling is unburrowed.

That's a good idea.
But I'm worried how long it would take for the dt to move.
And preferabely, I wouldn't want the dt to obstruct ground units.
I will try it though

You can use triggers to move the DT.

http://www.staredit.net/wiki/Burrow_Detection

You need to make sure that you don't use a 1x1 tile location. You need a location that is smaller than the unit which you want to detect when it's burrowed.

Oh i see how this works now.
Thank you very much rockz