Diving Beetle – All You Need To Know

We’re all aware of beetles that raid our pantries and feed on our crops, but did you know that some beetles prefer to live in water? The diving beetle is a unique creature that you simply must know about.

The diverse world of insects is always interesting, but aquatic insects are a special bunch.

This is probably just because their aquatic habitat makes them seem a bit more exotic than the land species we’re more acquainted with. 

Diving Beetle

Diving beetles tread the line between aquatic and land-dwelling as though they never knew a difference existed!

These babies are born in the water and spend most of their lives in it, but they are found on land as well.

Read on to learn more about this unique, confounding, and beautiful beetle.

What Are Diving Beetles?

Diving beetles, or predacious diving beetles, are a family of water beetles that earn their name due to their ability to dive underwater. 

Scientifically known as Dytiscidae, this family comprises more than 4,000 species. 

While they don’t usually fly over long distances, the diving beetles are adept swimmers. The streamlined structure of their bodies allows them to move swiftly through the water. 

Interestingly, their eyes have bifocal lenses that allow them to find water bodies more easily while migrating. 

Diving beetles are carnivorous insects that prey on various other aquatic organisms to sustain themselves.

Diving Beetle

What Do Diving Beetles Look Like?

While diving beetles share the dome-like shape that beetles are known for, their structure is a bit different from the beetles we’re more familiar with. 

As mentioned earlier, diving beetles have streamlined bodies that suit their aquatic habitat better.

They’re rather fat and oval, with the rear portion being wider than the front part. These beetles are two inches long on average, but some species are larger. 

The great diving beetle, for instance, grows up to three inches and is one of the largest aquatic insects.

Diving Beetle

The color varies from one species of diving beetle to another, with most of them being tan, black, or olive green. While they’re primarily of a solid color, there are exceptions. 

The sunburst diving beetle, for instance, has a black body with several large bright yellow spots. 

Many diving beetles, including the sunburst diving beetle, also have a carapace of a different color – usually orange or yellow. Such an appearance makes diving beetles easy to identify.

Diving beetles have well-developed compound eyes that serve them well while hunting for prey. They also feature chewing mouthparts and a pair of short and thin antennae.

Special Adaptations in the Diving Beetle

The diving beetle is not only an aquatic insect but also a predator. This calls for special adaptations to suit its habitat and feeding habits. 

Apart from the streamlined structure for efficient swimming and diving, they’re also capable of storing oxygen. This is how they survive while hunting underwater.

They carry air bubbles under their wing cases, known as physical gills. Although they can refill the oxygen reserves with oxygen extracted from the water, they consume the stored oxygen at a faster rate. 

Eventually, they have to come to the surface and refill the bubble.

Diving Beetle

Interestingly, these beetles have a completely different way of surviving underwater in the larval stage. 

Known as water tigers, diving beetle larvae have a snorkel-like organ to breathe while submerged.

Another important characteristic of these beetles is the appearance of their hind legs. While they have three pairs of legs like any other insect, the hind legs are particularly large and oar-shaped. 

These powerful legs allow them to push through water with ease. The hind legs also have a thick fringe of swimming hairs that make them even more suited for the purpose.

Where Do They Live?

These interesting aquatic beetles are more common than you might realize. 

You can find them in every continent besides Antarctica, though the species vary from one region to another. North America alone has more than 500 species of diving beetles.

They live in shallow water bodies, which makes them even more common in pools, lakes, and streams. 

Diving Beetle

In larger water bodies, they mostly stay among the vegetation close to the shore – away from fish that can potentially prey on them. 

Diving beetles prefer still or slow-moving waters and have adapted to almost every type of inland aquatic environment, including brackish water.

What Do They Eat?

Adult diving beetles are surprisingly good predators, capable of hunting prey larger than themselves. 

While they primarily feed on other invertebrates, tadpoles and fish are among their food sources too. Diving beetles chew and tear their prey into manageable pieces if they’re too big. 

If live prey isn’t available, you can also find them scavenging for carrion.

Diving beetle larvae share a similar range of food sources and are also adept predators.

Diving Beetle

Their voracious appetite and effective strategy of ambushing their prey have earned them the title ‘water tigers.’ 

The larvae lie still in wait for their prey, grabbing them and injecting them with toxic digestive juice as soon as they get close. 

The juice kills the prey and digests them partially, after which the water tigers consume the liquified remains.

What Is the Lifecycle of Diving Beetles?

The Predaceous Diving Beetle has a similar life cycle as most insects, with four prominent stages – egg, larva, pupa, and adult beetle. However, the larval stage deserves special mention due to the larvae’s ability to hunt.

  • Eggs: While diving beetles are aquatic insects, they don’t lay eggs in the water. Instead, the females lay them on vegetation on or above the surface of the water. Often, they choose spots close to frog egg clusters so that the tadpoles can sustain their larvae.
  • Larvae: The larvae drop into the water upon hatching. They prey on insects, insect larvae, crustaceans, small fish, tadpoles, etc., while molting through the instars.
  • Pupae: Once the larvae have finished the final stage of molting, they move out of the water and burrow themselves in mud. Here, they begin to pupate. This duration of the pupal stage may vary from a week to several weeks.
  • Adults: Once the metamorphosis is complete, adult diving beetles emerge and return to the water to continue their life cycle and reproduce.

Dytiscid beetles can live for several years. In cold regions in the northern hemisphere, they hibernate in frozen water bodies during the winter.

Diving Beetle

Where Do They Lay Eggs?

Adult diving beetles lay eggs on aquatic plants on or above the water’s surface. 

They choose the location such that the larvae hatching from those eggs can drop into the water easily. In many cases, they also cut into stems and secure the eggs strongly in place.

Can Diving Beetles Fly?

Members of this aquatic beetle family are capable of flight. Their hard elytra open up sideways to release the soft, membranous hindwings. 

In most cases, they just fly around locally to move to a different water body when the current one becomes unsuitable for their survival.

Do Diving Beetles Bite or Sting?

Although diving beetles don’t have stingers, they can still bite you with their chewing mouthparts. 

A diving beetle bite is painful, but they rarely bite at all. Besides, the pain usually subsides quickly and doesn’t leave any lasting effects. The same applies to their larvae, the water tigers too.  

Diving Beetle

Are They Poisonous or Venomous?

Thankfully, diving beetles do not carry any poison or venom potent enough to hurt humans. Even if you get bitten by a larva or an adult, there’s no need to worry or seek medical attention. 

The toxic digestive juices secreted by water tigers are effective only against the small organisms they prey on. It’s harmless to both humans and pets.

Are They Harmful to Humans as Pests?

Apart from the chances of getting bitten by a diving beetle, they aren’t harmful to humans. Diving beetles count as beneficial insects due to their predacious nature. 

They can feed on mosquito larvae and other unwanted pests and pest larvae in a pond, thus reducing the need for pest control treatments. 

However, if you’re trying to grow the toad population in your pond, diving beetles may pose a problem by hunting the tadpoles.

Diving Beetle
Boreal Diving Beetle

Can They Come Inside Homes?

As diving beetles live in aquatic habitats, you don’t have to worry about them coming inside your home. 

They spend most of their time in a water body, flying only when they need to migrate. In case a diving beetle ends up in your home, it did so on accident.

What Are Diving Beetles Attracted To?

Diving beetles are attracted to artificial lights, which is why they often end up in man-made pools. 

If you’re trying to attract diving beetles to your pond, maintain good water quality as they seek well-oxygenated water.  

How To Get Rid of Diving Beetles?

Unless they’re in a  swimming pool or creating an imbalance in the ecosystem of your pond, there’s no need to get rid of diving beetles. 

However, if you have to do it, using a strainer to remove the beetles manually is the easiest way. 

Don’t spray any insecticides in the water – it will harm the other life forms in the pond or individuals entering the pool.

Diving Beetle
Predaceous Diving Beetle

What Eats Diving Beetles?

While straining them out of the pond is a good idea, another way is simply to let natural predators do the work for you. 

When they are young (as in their larval stage), fishes, skunks, and raccoons like to have a go at them by picking them out of the water’s surface.

Fish are by far their biggest enemy, and most larger fish eat both larvae and adult diving beetles.

However, since the adults spend some time on land as well, they are often prey to larger birds and reptiles like geckos and lizards as well.

Wrapping up

As we can see, diving beetles are beneficial natural predators that can help keep your pool or pond free of unwanted pests. 

Whether as larvae or as adults, these bugs are always on the lookout for a good meal – and all your aquatic pests are a form of food for them.

Finding these beetles in a water body is also a good sign, as they prefer clean water with ample oxygen content. 

Thank you, reader – we hope it was an enjoyable read.

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