Do I have to keep the three key bugs in my inventory at the same time?

Yes. The Secret Tomb entrance only opens when Crescent Wing Butterfly, Wasp Moth, and Spiny Harvestman are all in your inventory at once. Selling any of them blocks the unlock until you catch another.

Why does the Crescent Wing Butterfly only spawn at night?

Crescent Wing Butterfly is a Moon Hollow bug that is time-gated to 6:30 PM in-game time. If you arrive during the day, the spawn does not appear — wait for night and try again.

How much does the Bone Net cost?

The Bone Net costs 200,000,000 cash from Anpu inside the Secret Tomb. The Scorpion Net (250,000,000) costs 50M more but trades luck for strength.

Is the Bone Net or Scorpion Net better?

Both are endgame. Bone Net has the highest luck stat and is best for rare and elusive bug hunting, including the Cave Mother and Secret Tomb undead bugs. Scorpion Net has higher strength and is best for heavy Desert bugs like the Colossal Sandworm. Most endgame players carry both.

Can I unlock the Secret Tomb without a Rune?

Yes. The Rune system is a separate grinding multiplier added in April 2026 and is not required to reach the Secret Tomb. You only need the three key bugs, the entrance in Dune Burrow, and enough cash for the Bone Net.

Secret Tomb Guide - Catch Bugs Wiki (June 2026)

📌 Quick summary:

The Secret Tomb is a hidden area inside Dune Burrow. You unlock it by carrying Crescent Wing Butterfly + Wasp Moth + Spiny Harvestman in your inventory at the same time, then walking into the tunnel between the Potion Traders and the waterfall. Inside, Anpu sells the Bone Net for 200,000,000 cash.

The Three Secret Tomb Keys

Crescent Wing Butterfly

Biome: Moon Hollow
Time: After 6:30 PM in-game
Tip: Bring a torch or light lure. It is a Tomb key, so slot it in your inventory — not your vivarium.

Wasp Moth

Biome: Deeproot Caves
Time: Any
Tip: A Royal Net or stronger is recommended for Deeproot Caves. Carry it alongside the Crescent Wing Butterfly.

Spiny Harvestman

Biome: Dune Burrow
Time: Dusk
Tip: Patrol burrow entrances near dusk. Keep all three bugs in your inventory when you go to the tunnel.

Step-by-Step Unlock

Start in Moon Hollow at night. Wait until the in-game clock shows 6:30 PM or later, then catch a Crescent Wing Butterfly. Do not sell or vivarium it.
Move to Deeproot Caves. Bring a light source and a Royal-tier net. Catch a Wasp Moth and keep it in your inventory.
Move to Dune Burrow. Patrol burrow entrances at dusk until a Spiny Harvestman spawns. Catch it. You should now have all three key bugs in your inventory.
Find the tunnel. With all three keys in your inventory, walk into the rocky tunnel between the Potion Traders and the waterfall in Dune Burrow. The entrance opens only when you carry the three bugs together.
Talk to Anpu. Inside the Secret Tomb, talk to the Anpu NPC. He sells the Bone Net for 200,000,000 cash.
Slot the Bone Net. Equip it for rare-hunting runs in caves, the Secret Tomb undead bugs, and any rare/elusive spawn window.

The Bone Net (Reward)

The Bone Net is the highest-luck net in Catch Bugs. It is sold exclusively by Anpu inside the Secret Tomb and costs 200,000,000 cash. It sits 50,000,000 below the Scorpion Net but trades 50M cash for roughly +1,877 luck over the Scorpion Net.

Net	Cost	Strength	Luck	Best for
Bone Net	200,000,000 cash	Lower	Highest in game	Rare & elusive hunting, Secret Tomb undead bugs, cave biomes
Scorpion Net	250,000,000 cash	Higher	Baseline endgame	Heavy Desert bugs (Colossal Sandworm), Dune Burrow grind

Recommended Setup Before You Attempt

Net: Royal Net (76K) is the minimum to clear Moon Hollow and Deeproot Caves. Bring it as a backup.
Lure: Crystal Lure for +75% EXP and 2.3x mutation chance while you hunt the three keys.
Vivarium: Fill your vivarium with rare or exotic bugs before attempting — it funds the 200M Bone Net cost while you grind.
Cash reserve: Have at least 200,000,000 cash on hand before entering the tunnel. Anpu only sells for cash, not a quest token.

Common Mistakes

Selling a key bug. The unlock fails if Crescent Wing Butterfly, Wasp Moth, or Spiny Harvestman is missing from your inventory.
Vivarium-ing a key bug. Vivarium slots are separate from inventory. Keys must stay in inventory.
Going to the tunnel in daylight. Crescent Wing Butterfly is time-gated to 6:30 PM; the unlock path includes a night spawn.
Arriving without 200M cash. Anpu sells the Bone Net outright, not as a quest reward.

📝 Note:

See also: Update Log for the March 2026 entry that introduced the Hollow, Advanced Meta Guide for cave and Secret Tomb undead-bug farming, and Net Tier List for the full Bone Net vs Scorpion Net comparison.