Use "Heart of Clear Water" to protect "Petit Moth" from being destroyed until you can Summon this card.
Use "Insect Barrier" to protect "Petit Moth" from being destroyed by your opponent's Insect-Type monsters until you can Summon this card. Just be sure to have "DNA Surgery" on the field and select Insect-Type. All monsters on the field will be treated as Insect-Types, making "Insect Barrier" very effective.
Use "Pixie Ring" or "The Seal of Orichalcos" so your opponent can only attack "Petit Moth" if you control no other monsters. With the latter, it will have 4000 attack as well.