Are Backswimmers Dangerous? Debunking Myths & Revealing Facts

Backswimmers, also known as water bees or water wasps, are aquatic insects belonging to the family Notonectidae.

These aquatic creatures are characterized by their unique swimming style, where they propel themselves through the water with their ventral side (belly) facing upwards. This peculiar technique has earned them the name “backswimmers.”

These insects are slender, oval, and have streamlined bodies designed for swimming in water. They possess long, oar-like hind legs with fine hairs, which they use for navigating through water bodies.

A Backswimmer

Backswimmers make their home in various aquatic environments, such as clear, still, and weedy waters, where they feed on a wide range of small aquatic organisms.

Although backswimmers are predators that prey on invertebrate and vertebrate organisms, including tiny fish fry and tadpoles, they pose minimal threat to humans.

However, some individuals may experience a painful bite if they happen to handle these insects carelessly.

Overall, backswimmers are fascinating creatures that hold great importance in the aquatic ecosystem, while their danger to human beings is quite limited.

Understanding Backswimmers

Physical Characteristics

Backswimmers, also known as water bees or water wasps, belong to the family Notonectidae. These aquatic insects have some unique features that make them stand out:

  • Light brown color
  • Reddish eyes
  • Slender, oval, streamlined body
  • Oar-like hind legs with fine hairs

The oar-like hind legs help backswimmers to propel themselves through the water with their ventral side facing upwards, giving them their common name of “backswimmers.”

Habitat and Distribution

Backswimmers can be found across various habitats, from man-made water tanks to natural waterscapes like ponds, lakes, and marshes.

In the UK, there are around four species that thrive in different aquatic environments. Their preferred habitats usually have the following characteristics:

  • Presence of vegetation
  • Still water or slow-moving water bodies

Some common habitats include open water butts and densely vegetated areas that provide shelter for the backswimmers.

These water bugs are known to compete with small fish for food as they prey on tiny fish fry, tadpoles, and other aquatic invertebrates.

Comparison Table of Backswimmer Habitats

HabitatProsCons
Water tanksEasy access for observation and researchArtificial environment
PondsNatural habitatCompete with fish for food
LakesLarger water bodyCan be harder to find
MarshesAbundance of vegetation and shelterMight not be accessible for humans

Backswimmers as Predators

Prey and Feeding Habits

Backswimmers, belonging to the family Notonectidae, are aquatic insects known for their predatory nature. They primarily feed on a wide range of prey such as:

  • Insects
  • Fish
  • Tadpoles

One defining characteristic of backswimmers is their sharp beak, also known as a proboscis. This piercing mouthpart allows them to be highly effective piercer-predators that can kill and suck the bodily fluids from their prey.

For example, they feed on tiny fish, larvae, and invertebrates like mosquitoes and water mites in freshwater habitats.

When hunting, backswimmers use their front legs to seize their prey, while using air bubbles to help them stay submerged and maintain their oxygen supply.

Role in the Food Chain

Backswimmers have a significant impact on the food chain in their ecosystems. As predators of small fish, tadpoles, and insect larvae, they play a crucial role in controlling populations of potential pests, such as mosquitoes.

However, they also serve as prey for various predators, including:

  • Birds
  • Amphibians (e.g., frogs and toads)
  • Larger aquatic insects (e.g., giant water bugs or “toe-biters”)

Their presence in the food chain provides a balance between the predator-prey relationship, ensuring the overall health of the ecosystem.

PredatorsPreyHabitat
Birds, Amphibians, Giant water bugsInsects, Small fish, TadpolesFreshwater, Still waters, Birdbaths

It’s essential to recognize that while backswimmers are predaceous and have a painful bite, their threats are typically limited to small aquatic creatures and not to humans or larger animals.

Are Backswimmers Dangerous

Bite and Its Impact on Humans

Backswimmers, belonging to the family Notonectidae, are known for their unique upside-down swimming behavior. They are predaceous insects that feed on a variety of aquatic creatures, such as:

  • Invertebrates
  • Small fish
  • Tadpoles

Backswimmers have a painful bite. Their bite injects a toxin that causes a burning sensation in humans, similar to a bee sting. However, unless someone is allergic to the toxin, the reaction is generally mild and short-lived.

Dealing with Backswimmers in Swimming Pools

Finding backswimmers in swimming pools can be concerning. Here are some preventative measures and removal methods:

  • Regularly clean the pool to minimize potential food sources
  • Use pool skimmers to physically remove the insects
  • Maintain proper pool chemistry to deter infestations

Comparison Table: Backswimmers vs. Other Swimming Pool Bugs

Bug TypeBite or StingHabitatSize
Backswimmers (Notonecta)Painful biteFreshwater0.5-1 inch
Water Boatmen (Corixidae)No biteFreshwater0.25-0.5 inch
Water StridersNo biteWater surface0.25-1 inch
Predaceous Diving BeetlesMild biteFreshwater0.5-1.5 inches

In summary, while backswimmers can deliver a painful bite, they are not significantly dangerous to humans.

By maintaining proper swimming pool hygiene and taking necessary precautions, one can effectively minimize encounters with these insects.

Recognizing and Differentiating Backswimmers

Comparison with Water Boatmen

Backswimmers, belonging to the family Notonectidae, and Water Boatmen, members of the Corixidae family, are both aquatic insects that can be spotted in underwater environments. Here’s a brief comparison between the two:

FeatureBackswimmersWater Boatmen
Swimming PositionBelly-upHead-down
DietPredatory (e.g. fish fry, tadpoles)Ingest living material (source)
Hind LegsLong, oarlike, with fine hairsSimilar, but not as pronounced
Keel Shape on BackKeeled like the bottom of a boatFlat

Other Similar Aquatic Insects

There are a few other aquatic insects that may be confused with backswimmers:

  • Greater Water Boatmen (Notonecta glauca): Also known as the common backswimmer, this species shares the belly-up swimming position of other backswimmers (source).
  • Pygmy Backswimmers (Family Pleidae): These true aquatic bugs inhabit clear, still, weedy waters and share some similarities with backswimmers, although they are members of a separate family (source).
  • Giant Water Bugs: These large insects can be differentiated by their considerably bigger size and powerful front legs used for capturing prey.
  • Water Wasps: Another name for backswimmers, emphasizing their streamlined body shape and predatory behavior.

Conclusion

In conclusion, backswimmers are fascinating aquatic insects that play a crucial role in the aquatic ecosystem.

They get their names for their unique swimming style. They may look a little intimidating, but they do not pose much threat to humans.

However, you must be careful of their bites as they can be painful. Understanding the physical characteristics, habitats, and feeding habits of these insects can help to eradicate any misconceptions about their danger to humans.

Readers’ Mail

Over the years, whatsthatbug.com has received hundreds of letters and some interesting images asking us about backswimmers. Scroll down to have a look at some of them.

Letter 1 – Backswimmer

Back Swimmer Pictures
When I was looking for the scientific name of backswimmers, I saw that you had a shortage of pictures of these cuties.

I just posted three pictures on my blog. If you want copies just drop me a line, or feel free to link to them if you want. I’ve been working on photographing underwater insects this past week. 🙂
http://macromath.blogspot.com/
Love your site!
Rachel

Hi Rachel,
We posted two of your Backswimmers, Family Notonectidae, and have linked to your site as well. Your photos are really great and a wonderful addition to our site.

Letter 2 – Backswimmer

Subject: what’s this??
Location: Grand Island Ny
October 21, 2015, 8:31 pm
Hiya. What kind of critter is this….hitched a ride home on the Hood of my truck. When I tried to get another angle pic it flew away.
Signature: Tracey

Backswimmer
Backswimmer

Dear Tracey,
This is a Backswimmer in the family Notonectidae, an aquatic True Bug that “often swims upside-down.

When resting at the surface, body is typically tilted with the head downward” according to BugGuide which notes they are also called Water Bees or Water Wasps because they can and do bite human that encounters them in the water, sometimes in swimming pools. 

As you observed, Backswimmers can fly as well, which enables them to fly from pond to pond in the event they cannot find food or the water dries up.  Backswimmers are aquatic predators.

Letter 3 – Backswimmer

Subject: What’s this bug
Location: Black Hills National Forest SD
September 15, 2016, 6:30 pm
Hello, these bugs were swarming around our house, falling on the roof like raindrops from the sky. We live in the Black Hills in South Dakota. Lots of ponderosa pine trees and some spruce. We saw them in September.
Signature: Dan

Backswimmer
Backswimmer

Dear Dan,
This is a Backswimmer, an aquatic True Bug that is also capable of flying.  Are you currently experiencing a dry spell?  It is possible that a nearby pond is drying out and these Backswimmers are seeking a new aquatic environment. 

You can compare your image to this BugGuide image of Notonecta undulata.  Of the family, BugGuide notes:  “Aquatic bugs that often swim upside-down. When resting at the surface, body is typically tilted with the head downward.” 

BugGuide also notes that they are also commonly called “Water Bees, Water Wasps” because they occasionally bite swimmers.

Thanks so much. That’s exactly what it is. Not knowing was driving us crazy.  Dan

Letter 4 – Backswimmer

Subject:  UFI – Unidentified Flying Insect
Geographic location of the bug:  Park County, Colorado 9300 feet
Date: 10/09/2017
Time: 05:40 PM EDT
I was draining our water feature yesterday and noticed this bug swimming underwater.  Its hind legs were really long, making it a good swimmer.  I fished it out of the pond and it flew away pretty quickly. 

Bright green between the eyes.
Can you ID it?  None of the sources I’ve looked at seem to have it.  Thank you!
How you want your letter signed:  Brad Klafehn

Backswimmer

Dear Brad,
As its name implies, this Backswimmer in the family Notonectidae swims on its back, with its ventral surface up.  Your individual looks like the one in this BugGuide posting from a high elevation in California that is identified as
Notonecta kirbyi

It is also reported from Colorado according to BugGuide’s data.  As you observed, Backswimmers can also fly quite proficiently, which serves them well should the pond they are hunting in dry out. 

Backswimmers are also called Water Bees or Water Wasps, according to BugGuide, because of their painful bite, a fact many swimmers and waders can confirm.


Authors

    by
  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

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