If you're unsure how to identify the queen by appearance alone, consider where you found the ant. Queens tend to be found at the center of an ant's nest. Queens tend to prefer moist areas, commonly found in rotting wood. If you found an ant hiding in a damp area of your home or outside, especially in damp wood, this is more likely to be a queen. The vast majority of ant types have larger queens, with bigger thoraxes, who are easily differentiated from worker ants. However, army ants are an exception. Army ants have queens with smaller thoraxes, who look very similar to the ants in this type of ant colony. It may be difficult,to identify the queen when working with these kinds of ants. Army ants are more oval-shaped in appearance than regular ants. They have antennas on their heads, as well as mouth pieces shaped like scissors. If you cannot find the queen, consult a professional exterminator. Ants can be a real problem in your home. If you're unable to discover the queen on your own, or identify the types of ants, look in your yellow pages for an exterminator.

TL;DR in Vietnamese:
Chú ý đến khu vực mà bạn tìm ra con kiến. Xem xét đó có phải là loài kiến quân đội hay không. Tham khảo ý kiến chuyên gia.