The druid pouch is an item first obtained during the Nature Spirit quest. Its main use is to protect the player against the ghasts that haunt the Mort Myre Swamp. To use it, you must first fill it with nature items obtained by casting Bloom (either with the item you're given during the quest or with a Silver sickle (b) near fallen logs, branches, or dead bushes and picking what grows.) You can also fill it up with Mort myre fungus which can be purchased from the Grand Exchange, but since they’re relatively high price, it's cheaper to fill the pouch during Sulliscep runs. Mort Myre stems and Pears also give more uses per fill as well, though spawn less frequently when bloom is used.
Once the pouch has been filled, it can be used against the ghasts. If you use it on an invisible ghast, or when one attacks, the pouch will activate, making the monster visible. It can then be attacked and killed. It also protects any food you have in your inventory from becoming rotten.
If lost, the druid pouch can be reclaimed from the inside of the Nature Spirit's grotto - one respawns near the grotto pool.
Building the fire of dehumidification is a strictly better, non-consumable alternative to druid pouches.