The Buggers are a powerful race of space-faring insectoid aliens, who have been warring with Earth for a long time. Humans and Buggers have not been able to communicate effectively, and were unable to negotiate for peace, so wherever each finds the other, they go to war. Ender is recruited to think better than they do and so win the war for good; Mazer explains how they communicate and think:
"The buggers don't talk. They think to each other, and it's instantaneous like the philotic effect... They aren't having a mental conversation between people with different thought
processes. All their thoughts are present, together, at once."
(Card, Ender's Game, Google Books)
This explains why they don't tend to have the same tactics as Humans; they are mostly controlled by the Queen, with no independent thought processes, and so have little autonomous activity. Their ships don't act alone, but operate as if parts of a body, moving unconsciously as the mind dictates. This communication makes them deadly because they don't have an individual fear of death, but it also opens them up to unconventional military tactics.
The buggers are aliens. They are technologically far more advanced than humans when they first encountered humans. The wars are brutal and there is no way to negotiate peace because the buggers don't talk. They communicate with their minds. Ender calls it "hive mind". The Queen is the only one with rational though, everyone else are as mundane as extra limbs and fingers: disposable. Because of this, communication is instant. Think of it like when you want to move your hand. Your brain sends the signal and your hand responds. However, this takes no time at all and happens naturally. Your hand doesn't have autonomy to defy your command. Likewise, the buggers follow their queen mindlessly and efficiently.
The buggers are aliens and they communicate tellipathiclly