BackSwimmer: All You Need to Know in a Nutshell

folder_openHemiptera, Insecta
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Backswimmers are fascinating aquatic insects known for their unique swimming style and intriguing characteristics.

These slender, oval, streamlined water bugs have a distinct appearance with keeled backs, resembling the bottom of a boat, and long, oar-like hind legs that have fine hairs, which they use for propulsion.

Interestingly, they swim with their ventral side (belly) facing upwards, hence their common name of backswimmers.

Their swimming technique often seems peculiar, as they move in a belly-up orientation while navigating through water.

Backswimmer

A notable feature of backswimmers is their ability to rest at the water surface with their abdomen tip protruding from the water in a tilted head-downward position.

Backswimmers are piercer-predators that feed on a variety of prey, including tiny fish fry, tadpoles, and invertebrates.

When comparing backswimmers to other aquatic insects, such as water boatmen, one significant difference is their method of capturing food.

While backswimmers have piercing beaks to suck bodily fluids from their prey, water boatmen lack this feature and instead ingest living material like diatoms as they swim along the bottom of a pond.

Both backswimmers and water boatmen play essential roles in the aquatic ecosystem and provide an engaging subject for nature enthusiasts to observe and study.

Overview of Backswimmers

Backswimmers are a family of aquatic insects belonging to the order Hemiptera and the family Notonectidae. They are commonly known as “true bugs” because they are a part of the “true bug” category.

These creatures have a unique size, usually ranging between 0.5 to 1 inch in length.

They have an interesting manner of swimming, gliding through the water belly-up using their long, oar-like hind legs. Their colors often include shades of gray, yellow, green, or tan.

Living underwater, Backswimmers exhibit some unique characteristics:

  • Streamlined, oval-shaped body
  • The back is keeled, resembling the bottom of a boat
  • Equipped with fine hairs on their legs for efficient swimming
  • Resting on the water surface tilted head-downward

Comparing the Backswimmer with a similar aquatic insect, the Water Boatman:

FeatureBackswimmerWater Boatman
Size0.5 – 1 inchSmaller
Swimming PositionBack-downwardHead-down
PreyInvertebratesDiatoms
LegsLong and oar-likeShorter
HabitatCalm, still watersPonds, slow streams

Habitat and Distribution

Backswimmers are aquatic insects found in various water bodies. They inhabit ponds, lakes, and even swimming pools.

These insects are commonly found with other aquatic life. They share habitats with: Amphibians and Invertebrates

Backswimmers have a wide distribution. They are native to places like the UK and Mexico

In different regions, they adapt to changing seasons. In winter months, backswimmers may display a brown coloration, blending in with their surroundings.

HabitatDistribution
PondsUK
LakesMexico
Swimming PoolsBoth

Backswimmer

Physical Characteristics and Adaptations

Body Structure

Backswimmers have a slender, oval, streamlined body adapted for swimming.

They have a keeled back, similar to the bottom of a boat1, with a silvery appearance due to air bubbles trapped on their body surface2.

Hind Legs

These insects have long, oar-like hind legs1. The legs have fine hairs which help with swimming1. The powerful hind legs allow for fast movement in the water, especially when chasing prey.

Mouthparts

Backswimmers are piercer-predators2. They have a sharp beak adapted for piercing and sucking the bodily fluids of their prey, such as:

  • Small invertebrates
  • Fish fry
  • Tadpoles2

Their beak can also inject venom, which can paralyze their prey2.

Eyes

These bugs have reddish eyes3 that enable them to detect prey and avoid predators in the water environment.

Wings

Backswimmers can fly, but they are clumsy fliers. However, they are attracted to lights so then can fly near lights in the evenings.

Scuba Tank-like Air Reservoir

Backswimmers have a unique adaptation in which they carry an air bubble attached to their abdomen tip1.

This air reservoir allows them to stay submerged for extended periods, hunting for prey and avoiding predators1.

Comparison: Backswimmers vs Water Boatmen

FeatureBackswimmersWater Boatmen
Body positionSwim belly-up1Swim head-down2
DietPredatory2Ingest living material2
MouthpartsBeak shaped2No piercing beak2
Air reservoirAir bubble1Absent

Behavior and Life Cycle

Feeding Habits

Backswimmers are piercer-predators that feed on various invertebrates and vertebrates, including tiny fish fry and tadpoles.

They swim head down along the bottom in search of food, using their piercing beak to suck out their prey’s bodily fluids ¹.

Backswimmer

Mating and Reproduction

During spring and summer, backswimmers mate and lay eggs on vegetation near the water surface.

They can produce multiple generations in a single season, with nymphs developing into adults throughout the warm months.

Predation and Defense Strategies

Backswimmers are agile swimmers and can escape predators by diving deep into the water.

They also have a unique defense strategy: releasing a foul-smelling substance when threatened.

Metamorphosis

The development of backswimmers includes:

  • Eggs
  • Nymphs (larvae)
  • Adults

As the nymphs grow, they undergo metamorphosis, shedding their exoskeleton several times before becoming adults.

Hibernation

In colder regions, backswimmers hibernate during winter months by burrowing into the mud at the bottom of water bodies.

They emerge in spring and resume their activities.

 Backswimmers
HabitatWater bodies
LifespanMulti-generational in a single season
FeedingInvertebrates, vertebrates
MatingSpring, summer
MetamorphosisEggs, nymphs (larvae), adults
HibernationIn colder regions, burrow into mud

Interactions with Humans and Other Species

In the Food Chain

Backswimmers belong to the family Notonectidae in the order Hemiptera and play a role as predators in the food chain. They feed mainly on:

  • Insects
  • Tadpoles
  • Small fish
  • Crayfish

These water bugs use their piercing beak to inject toxic saliva into their prey before consuming the bodily fluids1.

Backswimmer

Backswimmers as a Garden Presence

Backswimmers, also called water wasps or water bees, can be found in various water bodies like:

  • Ditches
  • Canals
  • Wildlife-friendly ponds

Creating a wildlife-friendly pond in your garden can help attract these insects. They are known to share their habitat with other aquatic species like:

Dealing with Backswimmers in Swimming Pools

In case backswimmers invade your swimming pool, you can employ these methods:

  • Careful manual removal
  • Avoid using chemicals, as they may harm other species

Painful Bites and their Treatment

Backswimmers can deliver a painful bite, often compared to a bee sting4. Here’s what you can do in case of a bite:

  1. Clean the bite area with soap and water.
  2. Apply a cold pack to reduce pain and swelling.
ComparisonBackswimmersBees
HabitatAquatic environments like ditches, canals, and pondsTerrestrial habitats, with nests in trees or underground
Insect orderHemiptera (true bugs)Hymenoptera (bees, ants, wasps)
Feeding habitsPredaceous, feeding on insects, tadpoles, and small fishPollinators, feeding on nectar and pollen from flowers
Impact of bitesPainful, with possible redness and swelling of the skinPainful, potential for severe allergic reactions in some cases

Conclusion

In summary, Backswimmers are insects that belong to the family Notonectidae. They have oval-shaped bodies, long legs, and prominent eyes.

They are found in freshwater habitats around the world, where they swim upside down near the surface. They feed on other aquatic animals, such as insects, tadpoles, and small fish.

They are both predators and prey in the aquatic food chain.

Backswimmers are unique and fascinating creatures that demonstrate the diversity and adaptation of life in water.

Footnotes

  1. Missouri Department of Conservation  2 3 4 5 6 7 8
  2. UWM Field Station  2 3 4 5 6 7 8 9
  3. MDC Teacher Portal 
  4. Backswimmers Water Bees; Water Wasps | MDC Teacher Portal 

Reader Emails

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

Letter 1 – Backswimmer in Martinique

Subject: Trying to identify bug in pool
Location: Martinique
November 22, 2014 10:00 am
Can you help identify what this is please ?
I found it swimming in our pool after a few days of heavy rains.
Signature: Matthew

Backswimmers
Backswimmers

Dear Matthew,
These aquatic true bugs are Backswimmers in the family Notonectidae.  According to BugGuide they are:  “Aquatic bugs that often swim upside-down. When resting at the surface, body is typically tilted with the head downward”
and they “Prey on other aquatic insects and sometimes on small vertebrates.” 

Backswimmers can fly, which enables them to seek a new home if their pond dries out.  We don’t know what would have caused them to relocate to your pool after the rains.

Daniel,
Thank you very much for your reply.
Fantastic info. My son has taken matters into his own hands and relocated them to another improvised pool. They’re doing well.

Can they fly far ? Perhaps the winds carried them a little further than normal.
Also, my pool is a salt based pool rather than chlorine, would that allow them to survive better than in the latter ?

Dear Matthew,
Since Backswimmers are predators, they will not remain in a body of water that does not provide a food supply.  Insects will not live in a chlorinated pool, but many insects will fall into the water. 

Backswimmers are air breathers, and if the chlorine is not strong, we imagine they can survive in a chlorinated pool.  We also believe there are some species that can inhabit brackish water, which is a blend of fresh and salt water.  They can fly considerable distances.

Letter 2 – Backswimmer from UK

Subject: unknown bug
Location: wigan,uk
April 26, 2014 4:41 am
hi, i would like to know if you could help me identify this bug/insect. it was found in my partners car, 3 weeks before this was found i started getting a lot of bites on my legs. i would really appreciate it if you could please help me to understand what it is as i have 2 children ages 2 and 4. thanks.
Signature: mel furda

Backswimmer
Backswimmer

Dear Mel,
This is a Backswimmer in the family Notonectidae, a group of aquatic insects that are capable of flying from pond to pond.  They are sometimes attracted to lights.  Backswimmers do have a painful bite, and they are sometimes called Water Wasps, but we doubt it is responsible for the bites you have gotten on your legs. 

Backswimmers will only bite if threatened, carelessly handled, or accidentally encountered while swimming.  They do not leave the water to attack people.  Look on UK Wildlife for some images of Backswimmers, which get their common name because they do swim on their backs.

Hi Daniel thank you for getting back in touch I can now put my mind to rest. Thanks Mel

Letter 3 – Mating Backswimmers

Mating Water beetles?
Been a while, but here is one I just couldn’t pass up! We have these little guys in our pool all the time in NW Indiana, yet this was the first time I saw some amourous activities happening….. These little beetles can fly if they are out of the water long, and were coupled for many minutes and not really interested in my closeups.. Hope you enjoy!
Michael Kovacs

Hi Michael,
These are Backswimmers and they are not beetles. They are True Bugs with piercing mouthparts in the family Notonectidae. Thanks for sending us your wonderful image.

Letter 4 – We’re guessing a Backswimmer from Australia

Can you guess?
Location:  Queensland, Australia
September 22, 2010 6:23 pm
Hi guys,
I took this shot this morning just outside my back door. There were several of these flying and hopping around. I know what it is but am seeing if you can guess. Only clue is, it’s not where you would expect to see one.
Signature:  aussietrev

Backswimmer???

Hi Trevor,
We are guessing that this is a Backswimmer in the family Notonectidae.  These aquatic insects can fly and they are attracted to lights.  Here is a BugGuide image.

Authors

  • 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.

    View all posts
  • 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.

    View all posts
Tags: BackSwimmer

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1 Comment. Leave new

  • No fooling the bugman, spot on, a boatman. There were about half a dozen flying and hopping around near my back door. There had been a large puddle there with all the rain we had and I think perhaps they hatched a bit too late. I caught all the ones I could and put them in the bird bath as they just kept flying into the wall and bouncing off.

    Reply

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