Yanme'e

The Yanme ' e are a race of aerial warriors which make up part of the unified conglomerate races of the Covenant, more popularly known as Drones, the name the Humans refer to them as. They are informally referred to by infantry as "buggers". Although they have been part of the Covenant for some time, they have just recently been put to use as combatants in the war against the humans. In the Halo 2: Collectors Edition instruction manual it is said they are suited to flight and combat in a gravitational-pull like Earth. This possibly means their home world is like our own.

Drones are insectoid and are covered in natural chitinous armor, although it doesn't provide that much protection. If you look carefully at a dead Drone, you can see small round technological/metal objects on its armor, assumed by some to be small shield generators employed to make up for the Drones' obvious weakness. It seems like other Covenant species, Drones share a ranking system in colored armor, but it is unclear who is leader. They do not interact with other species except to trade and serve in a military capacity, and their exact position in the Covenant Hierarchy is relatively unknown, although it is reasonable to believe they are of higher rank than Grunts and of lower rank than Elites.

After the Covenant Civil War began, the Drones took the side of the Brutes.

Drone Anatomy and Physiology
Drones are an insectoid species first encountered as a combatant by human forces during the First Battle of Earth. They are covered in a natural chitinous exoskeleton that provides some protection from ballistic and plasma based weaponry.

Their exoskeleton is covered with multiple bumps, grooves, indentations and markings. Many of the markings appear to be of use as camouflage. On close inspection these markings bear resemblance to a head. This is reminiscent of many terran insect species that bear markings that confuse predators into attacking less vital parts of their anatomy. This is indicative of the evolutionary path the Drones have taken, that they still bear the markings of their ancestry. They have the six limbs of an insect (although the last two appear redundant), compound eyes and two furry antennae that jut forth from a small head.

Drones are capable of powered flight, and have hovering capabilities. Using two large wings stowed beneath a protective carapace the Drone is able to take flight. However they can only do so for short periods of time before clinging to walls or landing for a period of rest. This may indicate that Drones are unused to flight within a gravitational field such as that generated by a planet or a Halo.

Drones are both fast and agile and pose a serious threat to enemies unused to dealing with aerial infantry. Although they possess sharp claws on their hands and spikes across the majority of their body, Drones shy away from close combat, preferring hit and run airborne attacks.

Combat
Drones prefer to stay at a distance and use long range tactics. However, they are skilled close-range combatants as well if the need arises. They always appear in swarms, and usually in large, open areas, where, combined with their agility, they are hard to target effectively. Drones also have the distinction of being able to board vehicles. They do not seem capable of driving them, but will claw mercilessly at the driver until he is killed.

They wield lightweight weapons such as the Needler and Plasma Pistol.They never charge up a shot of their Plasma Pistol to break a shield. They also enter battle in a pack (the number differs depending on the difficulty). Furthermore, they are not susceptible to headshots, though sniper weapons will always kill them with a single shot regardless of where it hits them. This is most likely due to a natural physical weakness. Drones never dual wield or have heavy weapons because they can only become airborne while lifting a small amount of weight. when fighting, they have to take frequent rests while in the air, probably due to the gravitational pull from Earth and High Charity. However it is unknown if they can last longer while in space. They are said to have replaced the Elite Rangers after the Covenant civil war began, probably due to their inherent maneuverability and skill in zero-G combat.

On Easy and Normal difficulty, the Drones are easy to kill and present no real threat. However, on Legendary, they can be an extremely deadly enemy to face. Their ability to fly means that if you have cover, they can still fly over and around you, and due to the reason they fight in packs, they can outnumber and kill you very quickly.

According to the second E3 Trailer, in Halo 3, Drones will have the ability to lift soldiers from the ground, similar to the Brutes.

If drones could have bigger weapons such as snipers, BRs, or swords they would very well be the strongest creatures in halo.

Halo 3
Little is known about them in the game and what their changes are, but it may be true that they have all the abilities they have before along with the ability to lift Marines into the air and possibly other small characters like Grunts.