There are now friendy Fairies roaming around Terraria that you can see floating around. There are three types of fairies in the game. They look like dots of light, pink, blue, or green, with a pair of wings around them. These creatures are beneficial to find secrets and bits of treasure for those searching for them.
You can find fairies in the underground reaches of Terraria. Start digging down into any biome and explore the various depths to find them. When you do find them, they will attempt to lead you to any nearby treasures or secrets you may have missed or had even more trouble finding. Of the three varieties, you need to remain wary of the blue ones because they can lead you to a treasure protected by traps.
All players have the option to capture these helpful fairies and place them into a bottle. To do so, you will need to acquire a bug net. You can purchase it from the Merchant NPC for 25 silver. You can summon the Merchant once you have an empty house space and have at least 50 silver in your inventory. Once you purchase the bug net, attempt to find a fairy and catch them with a net.
When you capture them with a net and place them inside of a jar, it will have the same color as the fairy you caught. You can place them in your house, and use them as decoration items.