Golden Beetle first appears as a sub-boss found in the Arqa Block on the 47th floor of Tartarus, encountered in a group of three. They impede the party's progress and must be beaten to proceed. They are later encountered as normal enemies in the Yabbashah Block of Tartarus, from floors 78 to 89.
The boss fight with the Golden Beetles always begins with the Beetles each getting a free turn, which they will use to cast Tarukaja on themselves. They also possess high defense, which makes it difficult to damage them. Bring Akihiko and Personas that know Zio spells to exploit their weakness to Electricity and gain easy All-Out Attacks. Depending on the turn order, it may be wise to not go for the all-out attack and force the bettles to waste a turn getting up. While not set as a weakness, these Golden Beetles take 25% additional damage from Fire and Wind attacks.
The Shadow is known as the Strength Beetle in Persona 4 and appears in Chapters 5 and 6 of the Void Quest within the Midnight Channel. Upon being defeated, they may drop the Golden Horn material. Selling 6 Golden Horns at Daidara will unlock the Plate Mail male armor in the shop.
In Golden, it may appear in Chapters 5 through 9. It may also drop Howlite for trade at Shiroku Pub.
Persona Q: Shadow of the Labyrinth
The Golden Beetle is a Shadow fought for the request, Investigate You in Wonderland replacing Queen of Hearts in order to obtain the Yellow Orb Key item, the Sphere of Fecundity from the void behind it. Completing the quest nets the Merit Badge, an accessory which grants +10 to HP and SP and +1 to all stats. The Bug Gold it drops allows Theodore to create the Silence Bow for Yukari, which inflicts Magic Bind, Heavy Punch for Akihiko, which inflicts Agility Bind, Cobra Boots for Chie, which inflict Poison, and Drowsy Shield for Kanji, which inflicts Sleep, each with a 15% chance to inflict their respective ailments.
Persona Q2: New Cinema Labyrinth
Golden Beetle is a rare appears in Area 4 of the second Theater, Junessic Land. It has an Affinity Barrier that helps it resist all incoming damage until it breaks when it becomes low on HP. Once its barrier breaks, it will become weak to Psy, Nuclear, Bless and Curse skills. The party can break its barrier faster by using Poison to quickly reduce its HP total. The Beetle Sap it drops is used to unlock the Obsidian Knife for the P5 hero, Primal Naginata for the P3P heroine, Mythic Sword for the P4 hero, Power Plate for Kanji Tatsumi and Raging Bull for Naoto Shirogane. Its Beetle Crystal is another component to unlock the Mythic Sword for the P4 hero and is also needed to unlock the Enhanced Armor once the boss of Junessic Land is defeated.