Throughout Hollow Knight Silksong, there are 28 regular Fleas to find, plus Vog in the Putrified Ducts who makes up the final number for the achievement once the Caravan reaches its final location. All of their locations are marked on the interactive map below:

Head into Deep Docks via either The Marrow or The Hunter's March. Beginning from the Bellway fast travel point, as indicated on the map above, head west to the room with falling lava. Time your jumps to get to the west side of the room, then continue up and to the right.

Silksong protagonist Hornet is far more agile than the Knight from Hollow Knight, especially in her diagonal downward slash. But this angled attack is causing lots of frustration for players online, especially in areas of the game where Hornet has to bounce off objects with the slash to get past deadly obstacles.