Shadow Insect
Shadow Insects are dark creations of Zant that are invisible to dwellers of the world of Light, and can only be seen using Wolf Link's senses. They have stolen the Light Spirits' light and cast their provinces into the Twilight, and the only way to bring the provinces back into the light is by destroying the 16 Shadow Insects hiding in each province holding the Tears of Light. The Tears of Light can only be held in the Vessel of Light
Twilit Bloat
Once Link obtains 15 Tears of Light in the Lanayru province, their queen will appear on Lake Hylia, holding the last Tear of Light. The queen is a bloated, giant Shadow Insect with tentacles instead of legs that can release electric shockwaves and dive under the water.
To defeat Twilit Bloat, Link must wait until it isn't charging him or is bursting with electricity. L-target it and leap onto its lower section. Keep a hold of the L button and repeatedly press A to bite it furiously. Repeat these steps a few more times and it will eventually fall into the water, lying on its back. Jump on its belly and use the energy field with Midna's help to attack its six tentacles at the same time. Once they are all destroyed in the same instant, it will shrivel up and die. This will release the last tear of light Link will collect, allowing him to finish returning light to Hyrule.