Cybister tripunctatus Click to enlarge image
Three-punctured Diving Beetle, Cybister tripunctatus Image: Andrew Donnelly
© Australian Museum

Fast Facts

  • Classification
    Species
    tripunctatus
    Genus
    Cybister
    Subfamily
    Dytiscinae
    Family
    Dytiscidae
    Super Family
    Caraboidea
    Suborder
    Adephaga
    Order
    Coleoptera
    Class
    Insecta
    Subphylum
    Uniramia
    Phylum
    Arthopoda
    Kingdom
    Animalia
  • Size Range
    2 cm - 2.3 cm

The large Three-punctured Diving Beetle lives under the water by breathing air stored beneath its wing cases.

Habitat

The Three-punctured Diving Beetle lives in still waters including ponds, lakes and river pools.

Distribution

The Three-punctured Diving Beetle is found hroughout Australia (except the south coast and Tasmania). There are about 20 species of predacious diving beetles (family Dytiscidae) in the Sydney region.

Feeding and diet

Three-punctured Diving Beetles are voracious predators, feeding on other insects, tadpoles and even small fish. The larvae are just as fearsome and capture their prey with piercing, grooved jaws through which they inject liquefying digestive juices. The prey 'soup' is then sucked up through the grooved jaws. The adult beetles have a powerful defensive chemical that they release to stun nearby fish.

Other behaviours and adaptations

Adult Three-punctured Diving Beetles fly great distances at night searching for water. They are also attracted to streetlights.


Cybister tripunctatus
Diving beetles are insects. They have four stages in their life cycle: egg - larva - pupa - adult. They have a streamlined shape, a pair of thin antennae and three pairs of legs. Their back legs have a thick fringe of swimming hairs. Image: Andrew Howells
© Australian Museum

Diving beetles are insects. They have four stages in their life cycle: egg - larva - pupa - adult.

Diving beetles have a streamlined shape, a pair of thin antennae and three pairs of legs. Their back legs have a thick fringe of swimming hairs.

Diving beetles live in ponds, lakes, billabongs and slow-running streams.

Diving beetles eat other invertebrates that live or fall into the water. Occasionally they also eat small tadpoles and fish. Adults tear larger prey into smaller pieces. Larvae pierce and pump digestive juices into their prey. They then suck out the liquefied remains.

Fish, frogs and water spiders like to eat diving beetles.

Adult diving beetles breathe by storing oxygen in a bubble underneath their wing cases.

Larvae have a siphon (like a snorkel) coming out the end of their body. They stick this siphon out of the water to get oxygen to breathe.

When diving beetles breed, the male fertilises the female's eggs internally. Female beetles often deposit their eggs into aquatic plants by making cuts in the stem.

Adult diving beetles often fly from one pond to another. They use light reflected from the water to find ponds. Sometimes they get confused, as light reflected off glass can look the same.