From Halopedia, the Halo wiki
As is standard within the Covenant ranking system, Yanme'e Majors outrank only Yanme'e Minors. They sometimes exhibit morphological differences from their Minor and Pupal cousins with the presence of three small protrusions on the head - though not all individuals have these. They may also have longer wings and fly faster than their lower-ranked brethren.
Yanme'e Majors can typically be distinguished by the presence of a light-blue exoskeleton or a dark brown exoskeleton, with a red tint. Like Minors, they are typically equipped with Type-25 plasma pistols and Type-33 needlers. Like all Yanme'e, Majors are equipped with anti-gravity technology that is attached to their wings that allow them to fly freely.
Some Majors deployed may also display no outward differences from their Minor brethren, keeping the same light-green colouration.
Yanme'e Majors are more skilled in combat than Yanme'e Minors and often wield Needlers or Brute Plasma Rifles. On Easy and Normal difficulties, they do not use the Needler's super-combine ability. However, on Heroic and Legendary difficulties, it is recommended the player takes cover frequently to regain lost stamina as Yanme'e Majors do use the Needler's super-combine ability.
Yanme'e Majors normally command a group of six to ten Yanme'e Minors. Some strategies are to stick one of the Yanme'e in the group with a Plasma Grenade, bombard them with Needler or dual-wielded Okarda'phaa-pattern plasma rifle fire. As with all enemies who move in groups, super-combining Needler rounds will produce an explosion that will most likely kill multiple Yanme'e in the group. One can also use ballistic fire, but some Yanme'e Majors have shields, especially in the presence of Engineers, hence making ballistic fire ineffective to a certain extent. Using Noob Combo is a good tactic. Yanme'e Majors also land on the ground much less often than their Minor brethren, making them less vulnerable to melee attacks.
In Halo: Reach, however, they are represented differently, with a more unique appearance. This may suggest that the Major is actually a caste that one must be born into in order to be able to hold the rank, or it might still be representative of biological growth that allows them to be promoted. The appearance of the Yanme'e Ultra is even more drastically unique.
The Yanme'e encountered in Halo 3 are split into Minor and Major ranks. However, outside of this name difference, the Majors exhibit no different behaviour from their Minor cousins, inheriting the exact same AI, model, textures, colouration and statistics. The Major description on Bungie.net was later reused for the Leader class of Yanme'e enemies (consisting of the Captain and Captain Major) in Halo 3: ODST, while Majors were given a blue colouration.
List of appearances