Mosquito Larva. The Mosquito exists in just about every waterway, they like the slower water. The Mosquito Larva is the second stage of the metamorphosis before it develops into a pupa. There is a couple of common way to check for these one is to get into a habit of carefully spooning your first fish of the day to check the stomach contents you will be surprised how often the Mosquito larva show up. Also you can run a small fine cloth net through the water edge on your arrival then check the contents in a glass of water.