Water Bugs and Other Aquatic Insects
Freshwater is home to countless species including fish, mammals, reptiles, and many different types of insects. Some aquatic insects will only spend part of their life cycle in freshwater, such as during the larval stages. As freshwater insects undergo metamorphosis, adults may have a similar appearance to larvae depending on whether they undergo complete or incomplete metamorphosis. Aquatic insects that spend their larval stages in the water are commonly referred to as macroinvertebrates. Insects that live in freshwater have developed a number of different adaptations that allow them to live in an aquatic habitat.
Mayfly larvae are commonly found in freshwater, particularly in streams. While they are not generally found in habitats with flowing water (known as lotic habitats), they are one of the most common aquatic insects and can live in a diverse array of freshwater habitats. Mayflies have a somewhat flattened body, allowing to to stay in place in moving water. They also have gills on their abdomen that allow them to pick up oxygen from the water. Mayfly gills canpresent themselves in two different forms including either a cluster of filaments or a row of plates; the gills are determined by their specific habitat.
As their name implies, stoneflies are commonly found in stony environments with fast moving water. As such, stoneflies are often found in small streams with cooler temperatures. Due to the fact that they live in fast moving water, they have very flat bodies that allow them to stay in place. They also have long gills with filaments. Upon undergoing metamorphosis, adult stoneflies are found on land as opposed to in the water
Dobsonfly larvae are quite common in freshwater environments. They are long and worm-like, with slightly flattened bodies and gills protruding from their abdomens. The most notable feature of dobsonfly larvae is their head, which has a large set of chewing, biting mouth parts. Dobsonflies are normally found in fast moving streams, where they spend most of their time burrowed in mud or silt. They undergo complete metamorphosis and adults live on land
Water bugs are true bugs, as opposed to many of the different types of insect larvae found in freshwater. Water bugs can refer to actual water bugs as well as water striders and water boatmen. These bugs are often found in still water as opposed to flowing water. Water bugs do not have gills and must come to the surface for air. However, there are several different types of water bugs that have the ability to carry bubbles of air that act as a portable air supply.
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Damselflies and Dragonflies
Damselfly and dragonfly larvae are prominent in freshwater environments. They typically resemble adult species but do not have wings. The similar appearance between larvae and adults is due to their incomplete metamorphosis. Dragonfly and damselfly larvae look very similar however the dragonflies are often larger around while the damselflies can be identified by the three gills projected from the end of their abdomen.
Finding Aquatic Insects
True water bugs will often be seen skimming across the top of the water but the different types of insect larvae that live in freshwater can be harder to spot. One can learn more about macroinvertebrates by finding a small stream. Take a bucket and scoop up some water and some rocks from the bottom of the stream. Using a magnifying glass, as well as the naked eye, examine the rocks and other materials. There is likely to be small insect larvae within the stream bed material. Seeing these insects up close can be a great learning experience.
Freshwater habitats are home to an astonishing amount of wildlife. In addition to the insects and larvae listed above, there are many other types of animals that call the water home. Learn more about aquatic insects by consulting the following resources.
- Common Aquatic Insects
- Aquatic Critters - Water Bugs
- Macroinvertebrates and Habitat
- Aquatic Macroinvertebrates
- North American Aquatic Insects
- Identification & History of Common Aquatic Insects
- Society For Freshwater Science - Aquatic Insects
- Aquatic Insect Larvae
- Caddisfly Larvae
- Caddisfly Houses
- The Eastern Dobsonfly
- Stonefly Larvae (Plecoptera)
- Aquatic Insects - Mayflies
- Dragonflies and Damselflies
- Macroinvertebrate Sampling
Written By: Lynn Taylor