Backswimmer Facts & Information 2023 (Notonectidae)

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Backswimmer Facts & Information Guide 2023 (Notonectidae)

A backswimmer insect in water
Backswimmers have fine hairs on the underside of their lower abdomen that hold air bubbles, enabling them to stay underwater longer. Photo by Katja Shulz / CC BY-SA 2.0

As their name suggests, backswimmers are a family of aquatic insects that swim upside down. This group belongs to the family Notonectidae, nested within the order of true bugs (Hemiptera). In addition, this group includes other well-known insects like stink bugs, aphids, and leaf hoppers. The name “Notonectidae” comes from the two Greek words “notos” (meaning “back”) and “nekta,” (meaning “swimming”). Backswimmers are commonly found in still, stagnant waters throughout the world and about 400 backswimmer species have been described.

Backswimmers can be found throughout the world and are most frequently found in still waters of ponds, lakes, swimming pools, and even bird baths. They thrive in stagnant water that is rich in aquatic vegetation or debris.

At first glance, these small aquatic insects appear very similar to the water boatman. Both groups are slender and have oval shaped bodies. This configuration allows the backswimmer to travel very efficiently through the water. The back legs of backswimmers are robust and long with feathery patches – these modified legs are what the insect uses to “oar” through the water. Unlike water boatmen, backswimmers do not have narrow, dark parallel line patterning on their backside. You can also distinguish them by watching their swimming style. Water boatmen swim right side up, while backswimmers swim upside down. Backswimmers are also rounder and tend to be lighter in color.

Backswimmers have a unique and exciting adaptation that allows them to remain underwater for up to hours at a time. On the underside of a backswimmer, there are two narrow channels; these channels are covered in very fine, inward-facing hairs which the backswimmers use to trap oxygen bubbles, extending the time they can spend underwater When the insect needs to dive under the water surface, it can draw oxygen out of this storage space, like a natural scuba tank. When the backswimmer depletes its oxygen source, it must return to the surface for more oxygen. This neat adaptation allows these very efficient hunters enough time to find food throughout the water column.

Backswimmer, water wasp
Aquatic true bug
Worldwide, primarily stagnant freshwater
6 months
0.8 cm-1.27 cm (⅓-½ in.)
Least Concern

What Do Backswimmers Look Like? (Backswimmer Appearance)

how to attract backswimmers to ponds
Backswimmers (pictured) lack the dark, thin, parallel back stripes present on water boatmen. Photo by Darron Birgenheier / CC BY-SA 2.0

As previously mentioned, backswimmers are commonly mistaken for water boatmen. Both aquatic insects are slender and ovoid. They also both have large and powerful back legs. Luckily, if you know what you are looking for, correctly identifying them is relatively straightforward.

One of the first things to pay attention to is location. Backswimmers are commonly found in artificial water sources like pools, fountains, and bird baths. In contrast, water boatmen are rarely found in artificial sources and prefer natural, slow-moving waters like deep, still creeks, ponds, lakes, and lazy rivers. The back of a backswimmer is keeled which this helps backswimmers swim in their characteristic upside-down position. While water boatmen have narrow, parallel lines on their backside, backswimmers do not have this feature.

Backswimmer Habitats – Where Do They Live?

several backswimmers and aquatic plants
Backswimmers prefer still or slow-moving water with vegetation. Photo by Peter / CC BY-NC 2.0

Backswimmers are usually found in ponds, quiet lakes, and slow-moving streams. They are hardy insects that can thrive in habitats that provide them with lots of vegetation, as they will utilize plants for cover so they can ambush prey. Backswimmers are even capable of surviving under the ice in freezing conditions!

In the winter, when temperatures drop, some backswimmer species will hibernate at the bottom of their lake or pond habitat when it freezes. Others will remain active, using their scuba-like adaptation to breathe under frozen waters and hunt for prey.

What Do Backswimmers Eat? (Backswimmer Diet)

a backswimmer eating a grasshopper
Backswimmers eat just about anything they can subdue, such as this grasshopper that foolishly leapt into the water. Photo by Kirill Ignatyev / CC BY-NC 2.0

Sources have described backswimmers as “voracious predators.” They tend to eat anything of a suitable size that they can catch. Backswimmers feed on various prey species, such as other aquatic insects, tadpoles, and even small fish. Surprisingly, they are also known to prey on other members of the same species. Backswimmers are known as “piercer-predators,” meaning they have a distinct method of killing and consuming their prey. First, they use their strong, sharp beak to pierce into unsuspecting prey. Once the backswimmer pierces its victim, it injects digestive enzymes into the prey’s body cavity, which paralyze the prey item and dissolve its insides. The backswimmer will then suck the bodily fluids out of the insect using its mouthparts.

To catch a meal, the backswimmer will dive beneath the water’s surface and ambush submerged prey. Additionally, backswimmers may lurk amongst submerged vegetation and wait for a prey item to swim by. Finally, if the backswimmer is hanging out in the bottom vegetation, it can release its grasp and float upwards to catch prey higher up in the water column.

While backswimmers are aggressive predators, they are by no means at the top of the food chain. Many fish, insects, and amphibians see these insects as excellent meals.

Are Backswimmers Dangerous or Venemous?

This is not recommended, but another way to tell the difference between these two aquatic bugs is to get bit. If the insect in question bites you and feels like a bee sting, you know you have a backswimmer on your hands. Water boatmen are harmless to humans and do not bite or sting. However, backswimmers inflict a sharp and painful bite, comparable to the feeling of a bee sting. Because they are known to bite people swimming in the water, they are often referred to as “water wasps.”

Although they bite and emit a toxin that helps immobilize and digest their prey, backswimmers do not pose a serious threat to humans. In other words, their bites are painful but do not cause any lasting harm. Backswimmers don’t bite humans unless they feel threatened, such as when they are picked up. In addition, they typically swim away from you, so you should not get bit if you refrain from handling them.

The Life Cycle of Backswimmers

several juvenile backswimmers fighting over food
Juvenile backswimmers are typically white with red eyes. Photo by gailhampshire / CC BY-SA 2.0

Like all other “true bugs,” backswimmers experience an incomplete metamorphosis known as hemimetaboly. During this process, they experience gradual developmental changes from egg to adult form. There are three stages: egg, nymph, and adult. Nymphal stages are similar to each other, and the development of wings marks the adult stage.

During the spring and summertime mating season, a male will rub his front legs against his rostrum or mouthparts, to make a unique sound and hopefully impress a mate. This process is known as “stridulation.” This is a similar method used by crickets when they rub their wings together to “chirp.” Backswimmers complete their life cycle in approximately six months, producing two generations per year.

If the male successfully attracts a mate, the pair will undergo a mating ritual. The female will then deposit her eggs on aquatic vegetation. She may also use a rock to lay her eggs on if there is no vegetation available. The eggs are usually clumped in groups of 10. Within a few weeks, the eggs hatch, and backswimmer nymphs will emerge. The spirits have white-colored bodies and red eyes.

When a backswimmer reaches the adult stage, it is nearing the end of its life and most backswimmers die soon after mating.

How to Attract Backswimmers to Ponds?

Backswimmers can be beneficial in your backyard pond because they help control the populations of other aquatic insects and are an excellent food source for many fish and wildlife species. However, they can inflict a painful bite on humans, so be wary if you see some in your pond.

Although backswimmers can bite humans when threatened, they are still more beneficial than they are harmful. For example, they feed on mosquito larvae, so if you live in humid environment that is conducive to mosquito propagation, they may help reduce mosquito numbers in your area.

It is certainly possible to attract backswimmers to your pond and there are few things you can do to achieve this. They are primarily attracted to stagnant water with abundant food sources. If you have some lights that turn on at night, place them by the edge of your backyard pond, or install some underwater pond lights, and backswimmers will be attracted to the new habitat. This will also attract water boatmen.

9 thoughts on “Backswimmer Facts & Information 2023 (Notonectidae)”

  1. We have a new pond in Indiana. We do not have any fish or plant life. We are having issues with a tiny (smaller than pencil eraser head) that bite. They are in the shallower part and come from the sand. Their bite does hurt. I would like to know how to kill them; any chemical options. I am not sure I want fish in our swimming pond. Thank you.

    • Live with them?! You do not want to be putting chemicals in your pond. Rather, I don’t want you to put checmicals in your pond, and I don’t even live on the same continent as you! Live and let live, I say.

  2. My pond is over run with back swimmers, they are killing everything in sight, there are so many and not enough preditors for them, what can I do?

    • Encourage predators. I assume it’s a wildlife pond (at least I hope so). They won’t eat everything in the pond. I have a small (8 ft x 8 ft) pond in the UK less than 2 years old. I have back-swimmers, frog tadpoles, pond skaters, pond snails and several species of dragonfly larvae all living there and it seems well balanced.
      Manage the surrounding area so it is wild (e.g. native herbs, annuals, other plants). Do NOT use any chemicals anywhere. Wait for the predators to arrive and see the natural balance emerge.

    • I was having the same problem, I started of with hundreds, most of the diving beetles left & they were even killing my dragonfly larvae. As the vegetation is thickening up & I’ve put a few more larger plants in around the edge more dragon flies are managing to crawl out. I’m also finding a lot of backswimmer corpses so I think they are killing each other & reducing their own numbers. I’m hoping next year it will be more balanced.

    • Hi Charlotte, depending on the size of your pond, you could stock it with insect-eating fish. I recommend you choose species that are native to your area as they will have the best chance of surviving outdoors.

      If possible, you can manually remove them with a pool skimmer and kill them by knocking them off into a bucket with oil or soapy water. Avoid touching them (or wear gloves) as annoyed backswimmers will bite!

      Unfortunately, removing backswimmers without removing all of the natural biota of a backyard pond is very difficult and requires a lot of time and energy. Depending on your area, backswimmers may be flying in from other sources of water that you do not have access to, making the task all the more difficult.

  3. I need help I have backswimmers in my chlorine swimming pool I would like to know how to get rid of them or where are they coming from

    • Hi Gail! Backswimmers are probably ending up in your swimming pool on accident as there would not be any food for them in a chlorine swimming pool. I suspect they are flying in from another water source and if that’s the case, it will be difficult to prevent them from ending up in your pool. The best thing you can do is keep the pool properly treated (the chlorine should kill them and deter them from settling in your pool) and skim the water before swimming to prevent any accidental bites.


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