Collecting all 30 Fleas in Hollow Knight: Silksong is necessary to reach 100% Completion. To fully complete the game, you need to find Kratt, Vog, Large Flea and 27 other Fleas hidden or stuck around Pharloom.

To start the Flea questline, consisting of Wish: The Lost Fleas and Wish: Ecstasy of the End, find Fleamaster Mooshka in The Marrow, at the first Flea Caravan location.

How to Complete Fleas Questline and Start the Flea Festival

1. Begin Wish: The Lost Fleas in The Marrow.
2. Find 5 Fleas to complete the Wish. It is now possible to move the Flea Caravan to western Greymoor, allowing you to skip Moorwing. This rewards a Flea Brew, a red Tool.
3. Find 12 total Fleas to move them to Blasted Steps. This happens only if the Last Judge is already defeated. This rewards a Spool Fragment #18. Find all Spool Fragments with our 100% Completion checklist.
4. Find 22 total Fleas to move them to Putrified Ducts, next to the Pale Lake. This rewards a Tool Pouch #4. Find all Upgrades here with our 100% Completion checklist.
5. Find all 30 Fleas to receive Egg of Flealia from Mooshka in Putrified Ducts.
6. In ACT 3, if all 30 Fleas are found, start the Wish: Ecstasy of the End in Bellhart to reach the Flea Festival. Beating the high scores in all 3 minigames yields the final Pale Oil, fourth Needle upgrade.
7. In ACT 3, if you've beaten Seth and found him around Pharloom multiple times, he will add new scores to the scoreboards. Beating these extremely hard challenges only rewards the Guardian's Memento, which is not required for any progression or achievement. Use our All Mementos checklist to find all Mementos.

Pro Tip: Finding all 30 Fleas can be difficult, as most are hidden in hard to reach spots, behind breakable walls or behind various puzzles. Use our All 30 Fleas checklist to find all of them. Avoid using interactive maps, if you don't want to be spoiled.

Unique Fleas in Silksong

Not all of the 30 Fleas in-game are the same. In Hollow Knight: Silksong, some of the Fleas are unique and can be interacted with in various ways. All of the unique Fleas will travel with rest of the Fleas.

Kratt

Kratt is a Lost Flea travelling around with his special backpack - which contains a Hot Springs spa.

You can find Kratt in Greymoor near Halfway Home. After he joins the caravan, Hornet can pay 10 Rosaries per each entry to use the spa.

Free Spa Access: There is a way to not pay - while Hornet baths, Kratt can be seen eyeing her through an airway duct. You can quickly jump and hit Kratt, which will make him apologetic. Kratt then allows you to use the spa for free.

Vog

Vog is a warrior Flea with the same goal as you - finding all Lost Fleas in Pharloom. Vog offers the locations of other Lost Fleas, but for a hefty price.

You can find Vog in Putrified Ducts, in the precarious path which required using Barnaks to complete a lengthy parkour challenge.

After Vog joins the Flea Caravan, they offer special map pins - which add other still lost Fleas locations to your Map. However, the Maps are very expensive, with most of them costing 150 Rosaries per every area.

Alternative: If you want to find Fleas without spending Rosaries or you want to avoid spoilers, use our All Fleas checklist.

Huge Flea

The Huge Flea is simply a giant, fluffy Flea, trapped at the top of the Memorium.

This is the only Flea that needs defeating. It has low HP and its moveset is composed of a single attack - quickly charging head-front.

Remember: Finding All Fleas is required for 100% Completion, including the 3 unique Fleas. Use our All Fleas checklist to track your progress, and reference our 100% Completion checklist to see how Fleas fit into your completion journey.