The Larva is a fiend in Final Fantasy X found on the Thunder Plains. It casts Thundara, and when its HP goes below 50%, it will start casting it on itself to recover HP and increase Magic Power. It is best silenced with Wakka's Silence Attack to avoid that. Larva is weak to Water. Another good technique is to use the Deathtouch weapon for Lulu that can be purchased in Guadosalam. Interestingly enough, if a character is equipped with Lightningproof armor and he/she Provoke the Larva, it will retaliate with Fire Magic instead of Lightning magic.