The life cycle of a bloodworm

Last Updated on July 23, 2021 by Jeffery Jago

Bloodworms are one of the stages in a non-biting Midge fly’s life cycle: the larva stage. The non-biting Midge fly, also known as chironomid or lake fly, looks very much like a mosquito but doesn’t bite.

These Midge flies can be a very beneficial source of food for fish and aquatic life throughout their life cycle. They also clean water through their diet of organic debris while in the larva stage.

Non-biting Midge flies are found inland and across coastal areas. They live in and near natural and man-made freshwater sources, such as reservoirs, streams, rivers, lakes, ponds, and water ditches. They have adapted to thrive in a variety of environmental conditions, such as stagnant and slow-moving water.

Midge flies go through four stages in their life cycle: egg, larva (bloodworm), pupa, and adult Midge fly. Let’s take a look at each stage in the non-biting Midge fly’s life cycle, with a closer look at bloodworms specifically.



Midges need still or slow-moving water to lay their eggs, which is why you will find their larvae in ponds, lakes, and in shallow, slow-moving rivers.

The female flies lay their eggs in a gelatinous mass on the water’s surface. Each mass may contain up to 3,000 eggs. The egg mass then sinks to the bottom of the water, where the eggs hatch over the next few days but within one week of being laid.



The larvae that emerge from the eggs hide in the mud and dig tiny tunnels, or tube-like structures, in the mud. This is their home for the next two to seven weeks.

They live off organic matter in the mud and water. They are not selective about what they eat and will happily consume human waste from sewage plants.

As the larvae get bigger, they make their tunnels bigger.

You will often find over 4,000 larvae per square foot in nutrient-rich water, where there is a lot for them to eat. Non-biting Midge larvae can thrive in polluted water with little oxygen because of their adapted ability to absorb oxygen in water.

The larvae of the non-biting Midge fly play an important role in the marine food chain. They serve as food for most meat-eating fish species, along with frogs, turtles, crabs, shrimp, salamanders, and snails.


The Midge fly will spend most of its life in this larva/bloodworm phase of development.

The larvae of the Midge fly are thin, segmented, and round. Their heads are usually darker than the rest of their bodies.

Their bodies take on a ‘C’ shape. This shape helps them to swim in the water by wriggling their bodies in figures of eight, cling to objects underwater, and burrow underground.

The larvae start off clear, whitish, light brown or olive green in color. Over time, they turn pink and then dark red in color. This red coloring comes from hemoglobin in their blood and gives them their name of being ‘bloodworms’.

Hemoglobin is made up of protein molecules that carry oxygen from the lungs to the rest of the body and carbon dioxide from the body back to the lungs. It is this iron-rich hemoglobin that facilitates breathing for the larvae in muddy water, where there is little oxygen. Their soft skin is designed to absorb dissolved oxygen in the water around them.


Bloodworms continue to grow and mature over a period of two to seven weeks. The speed of their development depends a lot on the temperature of the water. They then cease to exist and become pupae while hiding in their mud tunnels.

The pupa stage is initiated by hormones in the bloodworm. It is a time between larva and adulthood, and this is when the adult structures of the Midge fly are formed.

They spend only three days in this pupa phase, before swimming to the water’s surface and emerging as an adult Midge fly a few hours later.


At certain times of year, when the conditions are right, there may be several thousand Midge flies emerging from the water’s surface. Experts think that these swarms enhance survival rates and confuse predators.

Once a Midge fly has emerged from its pupa stage it looks a lot like a mosquito. Adult Midge flies are small with soft bodies and elongated legs, and they have long, narrow wings for flying.

These flies have a very short mouth tube, which means they can’t bite people. In fact, they are often called lind mosquitoes’ because even though they look like mosquitoes, they can’t bite like mosquitoes.

The flies mate with each other in a swarm soon after emerging from their pupae. Adult females then lay their eggs on the water’s surface while in flight, to start a new generation of Midge flies. Non-biting Midge flies can generate several generations of flies every year.

Adult Midge flies live only three to five days, without ever eating. Their main function is to mate and lay eggs before dying or ending up as food for fish, birds, dragonflies, or bats.



Bloodworms can be used as fishing bait or to feed fish in an aquarium. They are available freeze dried or frozen in many pet stores, or you can look for live bloodworms available in your area.

These bloodworms are a great natural food supplement for aquarium fish. This is because they provide nutrients and minerals from a food source (bloodworms) that fish would eat in their natural environment.


Frozen bloodworms are available as sheets or big blocks of worms.

When you want to feed your fish, place a cube of frozen bloodworms in a small container. Fill the rest of the container with tank water from your aquarium. Let the bloodworms thaw out to room temperature.

Strain the bloodworms to remove water and any juices. This minimizes the load on the filter as the fish will not necessarily eat the juices.

Start by feeding your fish a small amount of bloodworms to determine how much to feed them. You can increase the amount you feed them over time.

[I wrote as much as I could about the life cycle. I had to add the last two sections because I couldn’t submit the article with less than 1,000 words – please see if the new sections are relevant and helpful for you. There was no article heading or keywords, so I had to guess what would work for a pet website]