In Hollow Knight: Silksong, you will meet a character named Fleamaster Mooshka, who runs a little Flea Caravan. He will ask you to help him by finding and saving five Lost Fleas that are scattered around the world of Pharloom. Some are hidden in tricky places, and a few are protected by tough enemies. This guide will show you exactly where to find them and how to reach each one. Once you’ve rescued all five, you will get a special reward and unlock a shortcut to a new area.
All Flea Locations Guide

You get this task from Fleamaster Mooshka, who you will meet in the upper area of The Marrow with his Flea Caravan. He will give you a Wayfarer Task called The Lost Fleas, where he asks you to find and rescue 5 Fleas scattered across Pharloom. After you complete this first set, more Fleas will show up later for you to find.
Lost Flea #1


To get the lost Flea, head towards the higher part of the Marrow. Here, you will need to loop around from the left and make your way to the right side, where the Flea is stuck. There’s a lot of jumping involved, and you will also have to deal with flying enemies.
Lost Flea #2


The second Flea is in the Hunter’s March, but getting in is the tricky part. You will have to defeat a strong enemy called the Skarrguard at the entrance. Once you’re inside, just follow the trail of glowing buds, one of them will lead you straight to the Flea.
Lost Flea #3


This one is hard to miss. Right after you unlock the Sprint ability, head into the chamber on the left. From there, do some light parkour and climb up to the higher platforms to reach the Flea.
Lost Flea #4


For this lost Flea, go to the far fields. In the main article chamber, you will find a hidden room. Get near the right side, close to the bottom. There’s a breakable wall; smash it and head inside. As soon as you enter, a cage will trap you, and a Skarr Scout will ambush you from behind. Make sure you’re at full health and ready to fight.
Lost Flea #5


The final Flea is in the top-right area of Craw Lake. You will need to do some aerial jumping to get there. Watch out for the Tallcraw guarding the entrance, and keep an eye out for the Mite below; it can sneak up on you if you’re not careful.
Reward

Now, you need to go to the Fleamaster at the Flea Caravan. He will invite you to travel with the caravan. You don’t have to say yes; it’s just a shortcut that takes you to a later part of the game. If you choose to go with them, you will be taken to a new area beyond Greymoor and Halfway Home, where you will be able to reach Bellmont. You will be rewarded with the Flea Brew charm. It is a one-time-use item that boosts both your movement speed and attack speed when used.