Wuthering Waves‘ v1.1 Thaw of Eons update has added a whole area of Mt. Firmament, which has new creatures, including the Frostbug.
While you cannot capture the Frostbug’s Echo in Wuthering Waves like other Tacet Discords, you can kill them to get 20 Astrite per elimination. Astrites are essential to convene in different banners to pull for characters, so keeping a high stock enhances your chances of getting the desired Resonators.