Guides
Fields of Mistria Ancient Firefly Location Guide
Direct answer
Catch Ancient Firefly with the bug net in the Ancient Ruins on floors 81 through 99. It is a common insect available all day in every season and any weather, sells for 40 Tesserae, and belongs to the Ruins museum set. It can also be used in a common-insect terrarium and as one ingredient in Dragon-Forged Core. [S1]
At a glance
Quick Facts
| Location | Ancient Ruins floors 81–99 |
|---|---|
| Tool | Bug-catching tool / bug net |
| Season and weather | All seasons; any weather |
| Time and rarity | All day; Common |
| Sell and uses | 40 Tesserae; Ruins museum set, terrarium, and Dragon-Forged Core |
Do this first
Fastest path
- Reach the Ancient Ruins and search floors 81–99.
- Carry the bug-catching tool and scan eligible rooms at any time, season, or weather.
- Donate the first needed copy to the Ruins museum set or reserve it for the Dragon-Forged Core.
- Use surplus copies in a common-insect terrarium or sell them at the captured 40-Tesserae value.
Detailed guide
Ancient Firefly location
The structured item page places Ancient Firefly in the Ancient Ruins on floors 81 through 99. Its acquisition method is bug catching rather than fishing, mining, or foraging. Bring the appropriate bug-catching tool when searching the Ruins. [S1]
The pack does not provide one guaranteed floor, room layout, appearance count, or spawn probability within the range. Search throughout the eligible floors instead of claiming a fixed tile. Any best-floor route remains Pending verification (待确认). [S1]
Availability conditions
Ancient Firefly is classified as common and is available in all seasons. The table also says any weather and all day, removing seasonal, forecast, and time restrictions from the search. Those conditions make progression into the Ancient Ruins the main documented gate. [S1]
Common rarity does not promise immediate appearance because the source gives no exact odds. A missed floor or run can still occur under random spawning. Do not invent a nighttime requirement merely because the item is a firefly. [S1]
| Field | Captured value |
|---|---|
| Method | Bug catching |
| Location | Ancient Ruins floors 81–99 |
| Rarity | Common |
| Season | All |
| Weather | Any |
| Time | All day |
| Sell price | 40 Tesserae |
| Museum set | Ruins |
Sell value and museum donation
The captured sell value is 40 Tesserae. The item is donatable to the Ruins museum set, giving the first catch a collection use. A museum-focused player should check donation status before selling it. [S1]
The source does not provide the Ruins set reward or quantify town-rank progress in this pack. It also does not state that selling is the best use for duplicates. Reserve copies for crafting or terrarium plans before deciding what is excess. [S1]
Dragon-Forged Core ingredient
One Ancient Firefly is required in the captured Dragon-Forged Core recipe. The other core ingredients are 5 Monster Cores, 1 Mistril Ingot, 1 Pink Diamond, and 1 Medium Essence Stone. The core is crafted at the Dragon Forge under separate progression requirements. [S1]
This connection can make a seemingly common insect valuable late in progression. Keep at least one extra if the core is a near-term goal. The page does not claim that catching the insect alone unlocks Dragon forging. [S1]
Terrarium use
The item page says Ancient Firefly can be placed with four other common insects in a terrarium. After the relevant terrarium request, the setup can produce common fish bait and or common bug pheromones once every 3 days in the captured data. That is a production use distinct from museum donation and crafting. [S1]
The pack does not list the four best partner insects, complete request steps, placement interface, or output chance between the two products. It also does not prove that every later patch keeps the three-day timing unchanged. Verify the current terrarium description before building a quantified production schedule. [S1]
Gift reactions
The structured page lists Dell, Dozy, Henrietta, and Luc as neutral recipients for Ancient Firefly. It lists many villagers, including Adeline, Balor, Celine, Eiland, Juniper, March, Reina, Ryis, and Valen, as disliking it. The pack does not need the entire long exception roster to answer the location query. [S1]
The important practical warning is not to assume a glowing or rare-looking bug is a good gift. Use the current relationship profile for any recipient not named in a clean row. An unlisted reaction is not inferred. [S1][S2]
Source freshness
The current-style item page records Ancient Firefly as added in version 0.15.0. That history explains when the item entered the game but is not itself proof of the latest patch. Exact current drop behavior and recipe values should be rechecked after later updates. [S1]
The Fandom capture confirms the Bugs category but leaves acquisition, recipe, donation, and quest fields empty. Empty sections do not contradict the structured source and do not justify invented data. This guide uses the complete item page for all operational values. [S1][S2]
Catch and use checklist
Reach Ancient Ruins floors 81 through 99, carry the bug-catching tool, and scan eligible rooms at any time, season, or weather. Donate the first needed copy to the Ruins set, then reserve extras for a common-insect terrarium or Dragon-Forged Core. Sell only the surplus at the captured 40-Tesserae value. [S1]
No special nighttime window, weather event, or exact floor is required by the source. No spawn odds or guaranteed count are supplied. The supported route is broad but clear, and unresolved optimization details remain Pending verification (待确认). [S1][S2]
Conditions and exceptions
Version, conditions & exceptions
The item page records a version 0.15.0 addition; exact spawn behavior, terrarium timing, and later recipe values should be rechecked.
Last verified 2026-08-16. The collected evidence is ready for this page's stated scope.
Evidence trail
Sources & last verified
This page is limited to the collected sources below. Source conflicts, missing image data, and version-sensitive details remain labeled instead of being filled with guesses.
Last verified: 2026-08-16
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Evidence pack processed August 15, 2026 · Page updated 2026-08-16