Pastel Larva

What am I looking at?

This is the larva of a midge in the suborder Nematocera being viewed under polarized light. The colors you see are body parts with different molecular organization that shine in different colors under polarized light. You can see the head in yellow (1), some nerves in white (2), and the contents of its digestive system in orange/brown (3). Click on the right arrow to see a different view of this midge.

Biology in the background

The name midge refers to a large group of small flying insects. They are divided into two main groups: biting midges and nonbiting midges. Biting midges feed on the blood or bodily fluids of other animals and include insects that bite humans, such as black flies, no-see-ums, punkies, and sand flies. Almost all midges lay their eggs in water. When these larvae hatch, they begin to feed on algae and decomposing plant and animal matter. Certain species are active predators and feed on rotifers, protozoa, and microinvertebrates.

They progress through three or four larval stages, also known as instars, before they enter the pupal stage, from which they transform into adult flies. A few days to few weeks later, they emerge from the water to reproduce. Many midge species will synchronize the timing of this emergence and will fly from the water in swarms to maximize their mating potential and protect themselves from predators.

Midge larvae can vary in size quite a bit; the largest are up to 30 millimeters long, or a little bit bigger than the width of a human thumbnail.

Technique

These images were created using a form of light microscopy known as polarized light microscopy.