I can give you the 'lowdown' on this varmint. China is my fav vacation so I've run into this mission a few times.
When you receive the mission, go out to the map view of the village / area and you will be presented with a few icons on the map for the red assassin.
When you arrive at one of these locations, you won't see the bug immediately. You might see a black bug or nothing. Just hold that location and within 5 to 10 minutes of sim time you'll see one or more bright, more orange than red, dots on the ground.
Have your sim capture the red version. There is a chance your sim will fail at trapping the bug.
These little creatures are worth over 900 simoleans apiece. You might be tempted to drop the mission and just sell them instead.
Outside of the mission, I've never seen one, but then I don't run around looking either.
Hope this helps.
