A Look at Larvae

They’re just midges. If anyone pays attention to them at all, it’s to note how irritating they are when they swarm by the millions, here near Te Waihora/Lake Ellesmere. They are annoying at times, swarms so thick you can’t breathe without sucking in a few.

But there are few adults flying at this time of year. Most are still waiting out the winter as larvae underwater. Midge larvae are fun to look at under the microscope, as their exoskeletons are clear, allowing a great view of the inner workings of their bodies.

Seeing the inside of an insect larva helps one appreciate the job a young larva is tasked with—eat. Eat as much as you can and grow as fast as you can. A larva is little more than a mobile digestive system. The brownish streak you can see running the length of this midge larva is the animal’s gut, filled with the algae and other debris it has eaten. At the tail end, you can see, this little larva is having a poo.

Also at the tail end is a wee snorkel of sorts. These midge larvae can survive in low-oxygen water by sucking air from the surface using their snorkel. The silver lines meandering the length of the body are trachea that carry oxygen to all the insect’s cells.

This midge larva was tiny—about two millimetres long—it still has a while to grow before it’s ready to become an adult. But there are lots of other larvae out there getting ready to emerge with the upcoming warm days of spring.