The caterpillar-like Grubs trapped in glass jars across Hallownest, freed one nail-swing at a time, and offered back to their Grubfather for escalating rewards up to Grubberfly's Elegy.
Caterpillar is the colloquial name for the Grubs. According to the wiki, the small caterpillar-like creatures the Knight finds trapped in glass jars across Hallownest are formally called Grubs, and there are exactly 46 of them scattered across every major zone.
Per the wiki, the Collector is the one who caught them. He lives in the Tower of Love above the Soul Sanctum, jarring Grubs and the rest of Hallownest's small living things as part of his obsessive collection. Freeing every Grub eventually means killing the Collector, which unlocks a map showing every remaining jar location.
The wiki specifies that the Grubfather pays for the rescues. Each Grub returned to him raises a cumulative count, and at set milestones (5, 10, 15, 20, 31, 38, 46) he hands over Geo, Mask Shards, Pale Ore, a Rancid Egg, and two charms (Grubsong and Grubberfly's Elegy). Saving all 46 also flips a wiki-noted metamorphosis scene back at his chamber.
This guide covers what the caterpillar Grubs actually are, the Collector's role in trapping them, every Grubfather reward tier from 1 to 46 Grubs saved, the locator tools that make a completionist run feasible, and the cocoon-style metamorphosis ending the wiki frames as one of the game's quiet payoffs.
Grubs, the caterpillar-like creatures trapped in glass jars across Hallownest. 46 total.
the Collector in the Tower of Love. Killing him reveals every remaining Grub on the map.
the Grubfather in the Forgotten Crossroads. Rewards scale by total Grubs saved, not which Grubs.
Grubberfly's Elegy at 46 Grubs, plus the Metamorphosis achievement and the cocoon scene.The caterpillar creatures are Grubs. Per the wiki, they are small, soft, immature bugs that speak in high-pitched babbles the Knight cannot understand. They appear identical to one another visually, and the wiki specifies there is no difference in reward between which specific Grub is freed; only the cumulative count matters.
According to the wiki, every Grub emits a faint crying noise when the Knight is within a few rooms. The audio cue is the primary locator before the Collector's Map is acquired. After the jar is broken with the Nail, the freed Grub burrows into the ground and reappears in the Grubfather's chamber back in the Forgotten Crossroads.
The wiki notes that the Grubs talk frequently inside the jars, both before and after the Knight approaches. The pitch-shifted speech is the wiki-confirmed reason most players sense a Grub is nearby before seeing the jar. Dream Nailing a jarred Grub returns simple panicked lines about wanting to go home.
The Collector is the captor. Per the wiki, he is an optional boss who lives in the Tower of Love directly above the Soul Sanctum in the City of Tears. The wiki specifies that he jarred all 46 Grubs himself as part of his obsessive collecting of Hallownest's small living creatures.
According to the wiki, defeating the Collector unlocks the Collector's Map, which can be picked up from his chamber after the fight. Once the map is in the Knight's inventory, all remaining unfreed Grubs appear as map icons on every purchased area map. This converts a search-by-ear quest into a checklist run.
The wiki notes that the Collector fight requires the Love Key to access, which is found on the corpse of the Pale King's companion in Queen's Gardens. The Tower of Love door is on the eastern side of the Soul Sanctum elevator and only opens with the key equipped. In real runs, the Love Key + Collector kill is the prerequisite that turns Grub-hunting from a chore into a fast cleanup.
The Grubfather pays in escalating tiers. Per the wiki, the rewards stack on top of the per-Grub Geo drops and are tied to the running total of Grubs returned, not which Grubs were returned. He must be visited in person at each milestone.
| Grubs saved | Reward |
|---|---|
| 5 | Mask Shard |
| 10 | Pale Ore |
| 15 | Rancid Egg |
| 20 | Hallownest Seal |
| 23 | Grubfriend achievement |
| 25 | Pale Ore (second) |
| 31 | King's Idol |
| 38 | Grubsong charm |
| 46 | Grubberfly's Elegy charm and Metamorphosis achievement |
According to the wiki, Grubsong at 38 Grubs is the highest-utility reward in the chain. Equipping it returns SOUL every time the Knight takes damage, which makes it a staple charm across Path of Pain, the White Palace, and Godhome runs. The wiki specifies that Grubsong stacks with Deep Focus and Quick Focus for an aggressive heal economy.
The wiki notes that Grubberfly's Elegy at 46 Grubs is the flashier reward but the more situational charm. It fires a projectile beam from the Knight's nail at full health, which works only when undamaged. Skilled players run no-damage attempts with it; new players rarely find a use.
Stop by the Grubfather every time the total ticks up to the next milestone. Per the wiki, the rewards are not auto-mailed; the Grubfather hands them out only on in-person visits. Skipping a milestone visit and then rescuing the next Grub does not chain rewards, so players who batch the visits can miss intermediate pickups on a casual playthrough.
Iselda sells the Grub Pin. Per the wiki, the Grub Pin can be bought from Iselda's Dirtmouth shop for 180 Geo after the Knight has rescued at least one Grub. Once placed, the pin marks each rescued or still-jarred Grub on the map screen.
According to the wiki, the Grub Pin and the Collector's Map together turn the quest into a completionist checklist. Before the Collector kill, only rescued Grubs show on the map; after the Collector kill, every remaining jar shows up too. Most efficient runs schedule the Collector fight before any deep Grub hunting begins.
The wiki specifies that the audio cue still works even with the map markers on. New players often miss this and end up over-relying on the map; the audio is faster for narrow rooms where the map pin overlaps multiple platforms. In actual play, the combination of map pins plus audio is what makes the 46/46 run feasible inside a normal playthrough.
Saving all 46 Grubs triggers a quiet end-state scene. Per the wiki, after the final Grub returns to the Grubfather and the Knight rests at any Bench, the Grubfather can be found in his chamber lying on the ground, distended from swallowing all of the Grubs. The wiki notes that the Grubs can be distinctly heard cooing happily and contentedly inside him.
According to the wiki, the scene is the visual setup for the Metamorphosis achievement. The wiki specifies the community-supported reading: the Grubfather is acting as a cocoon while the Grubs undergo metamorphosis into Grubberflies, the same creatures whose silhouettes appear in the Grubberfly's Elegy charm icon. Team Cherry has never officially confirmed the reading, but the wiki notes it is the most consistent interpretation given the charm and the scene together.
The wiki notes that this is one of the few unambiguously positive endings any NPC group gets in Hollow Knight. Most characters die, fall to Infection, or are sealed away. The Grubs are reunited, the Grubfather is alive, and the cocoon scene implies the next stage of their life cycle. In practice, the wiki frames the 46/46 ending as the canonical "good outcome" players go out of their way to reach.
The caterpillar Grub quest connects to the Collector fight, Iselda's Grub Pin, and the Grubfather's reward chain. These spokes pick up the connected threads.
Game data and screenshots adapted from hollowknight.fandom.com, used under CC BY-SA 3.0. Original content remains the property of the wiki contributors and Team Cherry.