Backswimmer Facts & Information 2021 (Notonectidae)


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Backswimmer Facts & Information Guide 2021 (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

Backswimmers are a family of aquatic insects that swim upside down, just as their name suggests! They are from the insect family Notonectidae, which is nested within the order Hemiptera. The name “Notonectidae” comes from the two Greek words “notots” (meaning “back”) and “nektos,” (meaning “swimming”). Backswimmers are commonly found in still, stagnant waters throughout North America, the UK and the rest of the world. There are about 400 species of backswimmers known throughout the world today!

Backswimmers are very common insects, and they are most frequently found in the still waters of ponds, lakes, swimming pools, and even bird baths. They thrive in stagnant water that is rich in aquatic vegetation for habitat.

At first glance, these small aquatic insects are very similar in appearance to the water boatman. They are slender and ovaline in shape. This configuration allows the backswimmer to travel very efficiently through water. The back legs of backswimmers are very strong and long – these 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; this is one way to tell the species apart. You can also distinguish them by watching their swimming style. Water boatmen swim right side up, while backswimmers swim upside down. Backswimmers are also more round in shape, and tend to be lighter in color.

Backswimmers have a very unique and interesting adaptation that allows them to remain underwater for up to hours at a time. On the underside of a backswimmer, there are two thin channels; these channels are covered in very fine, inward-facing hairs. The backswimmer can use this area on its body to trap air bubbles! When the insect needs to dive under the water surface, it can draw oxygen out of this storage space, much like a natural scuba tank! When the backswimmer depletes its oxygen source, it must return to the surface for more. This neat adaptation allows backswimmers to hunt for food deep below the surface, and all throughout the water column. They are very efficient hunters!

BACKSWIMMER FACT SHEET
COMMON NAMES
Backswimmer, water wasp
SCIENTIFIC FAMILY NAME
Notonectidae
TYPE
Aquatic true bug
DIET
Carnivorous
NATIVE HABITATS
Worldwide, primarily stagnant freshwater
AVERAGE LIFE SPAN (IN WILD)
6 months
AVERAGE SIZE
0.8 cm-1.27 cm (⅓-½ in.)
IUCN RED LIST STATUS
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 mentioned above, backswimmers are commonly mistaken for a similar-looking insect, the water boatman. Both insects are slender and ovaline, and they are found in water. They also both have large and powerful back legs. However, if you know what you are looking for, it is fairly simple and straightforward to correctly identify them!

Backswimmers are more commonly found in man-made water sources like pools, fountains, and bird baths, while water boatmen are rarely found in artificial sources such as these and much prefer natural, slow-moving waters like deep, still pools in creeks, ponds, lakes, and lazy rivers. Additionally, backswimmers tend to be light brown in color, and have very large eyes that are dark red. The top side of a backswimmer is keeled in shape; this helps the individual to swim efficiently and quickly 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 most commonly found in ponds, or quiet lakes and slow-moving streams. They are hardy insects that can thrive in a wide range of environmental conditions. They thrive in habitats that provide them with lots of vegetation, as they will utilize plants to cling onto and wait for unsuspecting prey to pass by. Backswimmers are even capable of surviving under ice in freezing conditions!

In the wintertime when temperatures drop and life slows down, some backswimmers will hibernate at the bottom of their lake or pond habitat when it freezes over. Others will keep going about their lives, 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

Backswimmers have been described by sources as “voracious predators.” They tend to eat anything that they are capable of subduing! They feed on a variety of prey species, frequently hunting other aquatic insects, tadpoles, and even small fish. Surprisingly, they have even been known to prey on other members of the same species. They are what is known as “piercer-predators,” meaning that they have a very distinct method of killing and consuming their prey. They have a strong, sharp beak, which backswimmers use to pierce their unsuspecting prey. Once the backswimmer pierces its victim, it injects digestive enzymes into the prey’s body cavity. These enzymes and chemicals cause paralyzation of the prey, and begin to dissolve its innards! The backswimmer will then suck the bodily fluids out from the body cavity.

In order to catch a meal, the backswimmer will dive down beneath the water’s surface to catch submerged prey. If the backswimmer is hanging out in the bottom vegetation, it can release its grasp and float upwards to catch prey that is higher up in the water column.

While backswimmers are aggressive predators, no doubt, they are by no means at the top of the food chain! Many species of fish, insects, and amphibians see these insects as a great meal.

Are Backswimmers Dangerous or Venemous?

Here’s another way to tell the difference between these two aquatic bugs: if the insect in question bites you and it feels like a bee sting, you know that you have a backswimmer on your hands. Water boatmen are harmless to humans, and do not bite or sting. Backswimmers, however, are a different story. They emit a bite that is sharp and painful, 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 technically emit a toxin that helps immobilize their prey, backswimmers are not dangerous. If they bite you, it’ll hurt initially but won’t cause any lasting harm as they don’t possess nearly enough toxin to harm anything more than a few times their own small size. Generally speaking, backswimmers don’t bite humans unless they feel very threatened (such as when someone is trying to capture them). They typically will swim away from you, so just try to keep your space from them, don’t handle them, and you should be just fine.


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 incomplete metamorphosis – this means that they experience gradual developmental changes from egg to adult form. There are three stages: egg, nymph, and adult.

During the mating season in the spring and summertime months, a male will rub his front legs against his rostrum (the beak-like appendage) to make a unique sound called “stridulation.” This is a similar method used by crickets when they rub their wings together to “chirp!” This sound is meant to attract a female backswimmer as a mate. Backswimmers complete their life cycle in approximately 6 months, so they tend to produce two generations per year.

If the male is lucky in attracting a mate, the pair will undergo a mating ritual. The mated female will then deposit her eggs hidden in or on aquatic vegetation. If there is no vegetation in the habitat, then she may use a rock to lay her eggs on. The eggs are usually clumped in groups of 10. Within a few weeks, her eggs will hatch and backswimmer nymphs will emerge. The nymphs have white colored bodies, and red eyes.

When a backswimmer reaches the adult stage, it is nearing the end of its life. Most backswimmers die fairly quickly after mating and reproducing.


How to Attract Backswimmers to Ponds?

Backswimmers can be very beneficial to have around in your backyard pond because they provide some key ecosystem services – they help control the populations of other aquatic insects, and are a great food source for many species of fish and wildlife. They can inflict a painful bite on humans, but this isn’t harmful beyond the initial pain.

Although backswimmers do have a tendency to bite humans on occasion when threatened by them, they are still much more beneficial than they are harmful. They often feed on mosquito larvae, so if you live in a muggy, humid environment that is conducive to mosquito propagation, then they may provide you a huge service by keeping these pests at bay.

With the right environmental conditions, you can easily attract backswimmers to your pond if you are interested in doing so! They are attracted to stagnant water with ample food sources, and artificial light. 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 surely be attracted to the new habitat.

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