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Darwin’s Beetle (Chiasognathus grantii)

Darwin’s beetle belonging to the stag beetle family is indigenous to Chile and Argentina. It derives its name after Charles Darwin, credited of having collecting this species during HMS Beagle’s second voyage of which he was a part. The beetle is also called by a host of other names like the Chilean Stag beetle after its place of origin. However, one could rarely spot them since they have eventually become vulnerable species. In fact, these beetles closely remain on the verge of extinction, global climate change being one of the main reasons.

Darwin Beetle

Scientific Classification

  • Family: Lucanidae
  • Genus: Chiasognathus
  • Scientific name: Chiasognathus grantii

Physical Description and Identification

Adult

Size: Males: 60 – 90 mm (2.4 – 3.inches); Females: 25 – 37 mm (0.98 – 1.46 inches)

Color: From the paintings found in Chile, it has been deduced that they have a metallic green body with an iridescent red shine. The wing covers appear chestnut brown with shiny green patches.

Chiasognathus grantii

Other Characteristic Features: They exhibit sexual dimorphism, the males being larger having a stronger mandible than females. The males’ upper mandibles appear longer than their bodies, with finely serrated patterns. Other physical features seen in both sexes include small eyes, hairy antennae, and broad thorax. The front and back portions of their body also have dense coverings of short and pale-colored hair.

Larva

Because of these species’ rare availability, not much detail remains available about the larva’s identification. However, they mainly feed on the dead wood.

Pupa

The pupal phase takes place within the dead wood, where the larva thrives.

Egg

The eggs appear small and primarily round, laid near the rotting wood.

Quick Facts

Other NamesChilean stag beetle, Grant’s stag beetle
Adult lifespan1 – 2 years (like other members of its family, though exact numbers not recorded)
Duration of larval stageNot recorded (though they spend a major part of their lives as a larva)
DistributionChile, Argentina
HabitatMostly in the Nothofagus (southern beeches) forests
Common PredatorsBird, rat, fox, bats
Seasons active fromNot recorded
Host PlantsSouthern beeches
Diet of larvae and adultsLarvae: Dead or decayed wood
Adults: Juices of trees
Chilean Stag Beetle

Identifying the Damage Caused by Them

Since they mainly feed on the dead wood, these beetles do not cause too much damage.

Did You Know

  • These beetles have many local names like cantaria,  cacho de cabra, and ciervo volante in Spanish. In Mapuche, a language spoken in South-central Chile, people often call them llico-llico.
  • A few synonyms of the Darwin’s beetle’s species names include Tetropthalma chiloensis, and Chiasognathus pygmaeus.
  • While collecting these species, Charles Darwin mentioned that though the males had large mandibles, their jaws were not strong enough.  So if the latter bit, it would not cause a painful sensation.
  • The fight between two male beetles is a sight to see since the stronger opponent throws the weaker one down to the ground from a height of approximately 20m.
Grants Stag Beetle

Image Source: faculty.ucr.edu, t3.ftcdn.net, t4.ftcdn.net, 64.media.tumblr.com

Darwin’s beetle belonging to the stag beetle family is indigenous to Chile and Argentina. It derives its name after Charles Darwin, credited of having collecting this species during HMS Beagle’s second voyage of which he was a part. The beetle is also called by a host of other names like the Chilean Stag beetle after its place of origin. However, one could rarely spot them since they have eventually become vulnerable species. In fact, these beetles closely remain on the verge of extinction, global climate change being one of the main reasons.

Darwin Beetle

Physical Description and Identification

Adult

Size: Males: 60 – 90 mm (2.4 – 3.inches); Females: 25 – 37 mm (0.98 – 1.46 inches)

Color: From the paintings found in Chile, it has been deduced that they have a metallic green body with an iridescent red shine. The wing covers appear chestnut brown with shiny green patches.

Chiasognathus grantii

Other Characteristic Features: They exhibit sexual dimorphism, the males being larger having a stronger mandible than females. The males’ upper mandibles appear longer than their bodies, with finely serrated patterns. Other physical features seen in both sexes include small eyes, hairy antennae, and broad thorax. The front and back portions of their body also have dense coverings of short and pale-colored hair.

Larva

Because of these species’ rare availability, not much detail remains available about the larva’s identification. However, they mainly feed on the dead wood.

Pupa

The pupal phase takes place within the dead wood, where the larva thrives.

Egg

The eggs appear small and primarily round, laid near the rotting wood.

Quick Facts

Other NamesChilean stag beetle, Grant’s stag beetle
Adult lifespan1 – 2 years (like other members of its family, though exact numbers not recorded)
Duration of larval stageNot recorded (though they spend a major part of their lives as a larva)
DistributionChile, Argentina
HabitatMostly in the Nothofagus (southern beeches) forests
Common PredatorsBird, rat, fox, bats
Seasons active fromNot recorded
Host PlantsSouthern beeches
Diet of larvae and adultsLarvae: Dead or decayed wood
Adults: Juices of trees
Chilean Stag Beetle

Identifying the Damage Caused by Them

Since they mainly feed on the dead wood, these beetles do not cause too much damage.

Did You Know

  • These beetles have many local names like cantaria,  cacho de cabra, and ciervo volante in Spanish. In Mapuche, a language spoken in South-central Chile, people often call them llico-llico.
  • A few synonyms of the Darwin’s beetle’s species names include Tetropthalma chiloensis, and Chiasognathus pygmaeus.
  • While collecting these species, Charles Darwin mentioned that though the males had large mandibles, their jaws were not strong enough.  So if the latter bit, it would not cause a painful sensation.
  • The fight between two male beetles is a sight to see since the stronger opponent throws the weaker one down to the ground from a height of approximately 20m.
Grants Stag Beetle

Image Source: faculty.ucr.edu, t3.ftcdn.net, t4.ftcdn.net, 64.media.tumblr.com

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