Its cause of the wait. Instead, make a dummy unit, with 200 health, model file .mdl, locust ability, and then say
Unit enters playable map area
Action------------------------------------
Create 1 dummy for player 1 (red)
add last created unit to dummy units
And then
Event-----------------------------------
Time - Every .02 seconds
Action----------------------------------
Unit Group - pick every unit in dummy units
Set picked unit life to (picked unit life - 40
And then
Event----------------------------------
Unit dies
Condition------------------------------
Unit is in unit group "Dummy Units"
Action---------------------------------
Unit Group- remove dieing unit from Dummy Units
Special Effect- Create some special effect at position of dying unit
Special Effect- Destroy last created special effect