They now have to find other food sources. They usually go from planet to planet consuming its inhabitants. They usually incapacitate their victims and drain them while they're still alive. They use ION weapons to render other ships immobile and useless. They then board the ship and eat whoever was on it. They can live up to three weeks without feeding.
They live 150 years on average. They are not necessarily smarter than humans but they are more technologically advanced. They use queens to birth everyone. Every 1 in 10 000 females are queens. They can only eat creatures with red or green blood, because they feed of haemoglobin (or haemoglobin like) blood. They prefer red blood over green blood. They rely on the iron in the blood.