For the Ariados situation it is finished and it rewards you a hidden ability Spinarak with attack order, you need to do several steps that seem really disconnected. Those steps being speaking to an NPC in front of the professor's lab while naked to give you the blueprint to make clothes, speak to the bug catcher that lets you craft bug gems, speak to the female NPC in the house on the ranch to buy the clothes crafting recipe, 10k normally 6k after you are done with the ranch quest, and then talk to the male NPC to craft it and my least favorite part being you have give up your only silk scarf to make the clothes needed. This is probably not the most detailed breakdown or properly explained.
The silk scarf is my least favorite part since there is no replacement for it outside of excavating a blank plate from the caves which is weird. Also the bug gems are bugged in the mining minigame, they are invisible you only know they are there due to the item discovery chime, so it just seems better to craft them.