Home / Stag Beetles (Lucanidae) / Rainbow Stag Beetle (Phalacrognathus muelleri)

Rainbow Stag Beetle (Phalacrognathus muelleri)

Rainbow stag beetle of the stag beetle (Lucanidae) family is indigenous to several parts of Australia, particularly New Guinea and Queensland. These beetles generate a magnificent look mostly because of their rainbow-colored metallic appearance, especially on their wings and bellies. They are the only species of the Phalacrognathus genus with a close relation to the Lamprima genus.

Rainbow Stag Beetle

Scientific Classification

  • Family: Lucanidae
  • Genus: Phalacrognathus
  • Scientific name: Phalacrognathus muelleri

Physical Description and Identification

Adult

Size: Males: 24 – 70 mm (0.94 – 2.76 inches); Females: 23 – 46 mm (0.91 – 1.81 inches)

Color: They mostly have a green, red, or blue body with a metallic shine, especially on their back.  Besides this, their mandibles and legs are black.

Other Characteristic Features: Sexual dimorphism is visible when it comes to their physical features. The males have longer and more curved mandibles and antennae than their female counterparts.

Phalacrognathus muelleri

Larva

The larval stage goes through three instars, and in the final phase, they have a white segmented body with an orange facial patch. They mostly inhabit rotting and wet wood, mainly close to the white-rot fungi, and take about three years to mature into adults. 

Rainbow Stag Beetle Larvae

Pupa

They remain as a larva for a year, after which they enter their pupal phase, most of which takes place within the cells or chambers. When the pupa emerges into an adult, their wings remain soft and white at the beginning taking up to a week to attain their original color.

Rainbow Stag Beetle Pupa

Egg

The females lay about 50 eggs in rotting wood that hatch in a week. Over the period, the egg becomes twice its original size, and the larva can be seen within it.

Quick Facts  

Lifespan1 year
Duration of larval stageAbout 3 years
DistributionParts of Australia, particularly the coastal regions of northeastern Queensland, as well as New Guinea
HabitatMostly in the rainforest regions
Common PredatorsCat, kestrel, crow, foxes
Seasons active fromMostly during summer (march – July)
Host Plants Not recorded
Diet  of larvae and adultsLarvae: Decayed wood
Adults: Decayed wood, alongside sap, nectar, and fruit of their host plants
Rainbow Stag Beetle Picture

Identifying the Damage Caused by Them

Though they mostly feed on rotten wood and saps of trees, reports of their damage to the host plants remain unrecorded.

Did You Know

  • The two subspecies of this beetle include Phalacrognathus muelleri muelleri (Queensland), and Phalacrognathus muelleri fuscomicans (New Guinea).
  • Scottish naturalist and zoologist Sir William Macleay named it Phalacrognathus muelleri to honor the German-Australian physician, Baron Ferdinand von Muelle.
  • Their bright, vibrant coloration makes them an object of interest for beetle collectors, though the color eventually fades once they die.
  • Because of their long lifespan and less aggressive nature, these beetles make for great pets. They do well in households with kids since their not so large mandibles do not cause much harm even if they accidentally sting someone.

Image Source: i.pinimg.com, naturesface.com.au, jonathansjungleroadshow.co.uk, live.staticflickr.com, jonathansjungleroadshow.co.uk

Rainbow stag beetle of the stag beetle (Lucanidae) family is indigenous to several parts of Australia, particularly New Guinea and Queensland. These beetles generate a magnificent look mostly because of their rainbow-colored metallic appearance, especially on their wings and bellies. They are the only species of the Phalacrognathus genus with a close relation to the Lamprima genus.

Rainbow Stag Beetle

Physical Description and Identification

Adult

Size: Males: 24 – 70 mm (0.94 – 2.76 inches); Females: 23 – 46 mm (0.91 – 1.81 inches)

Color: They mostly have a green, red, or blue body with a metallic shine, especially on their back.  Besides this, their mandibles and legs are black.

Other Characteristic Features: Sexual dimorphism is visible when it comes to their physical features. The males have longer and more curved mandibles and antennae than their female counterparts.

Phalacrognathus muelleri

Larva

The larval stage goes through three instars, and in the final phase, they have a white segmented body with an orange facial patch. They mostly inhabit rotting and wet wood, mainly close to the white-rot fungi, and take about three years to mature into adults. 

Rainbow Stag Beetle Larvae

Pupa

They remain as a larva for a year, after which they enter their pupal phase, most of which takes place within the cells or chambers. When the pupa emerges into an adult, their wings remain soft and white at the beginning taking up to a week to attain their original color.

Rainbow Stag Beetle Pupa

Egg

The females lay about 50 eggs in rotting wood that hatch in a week. Over the period, the egg becomes twice its original size, and the larva can be seen within it.

Quick Facts  

Lifespan1 year
Duration of larval stageAbout 3 years
DistributionParts of Australia, particularly the coastal regions of northeastern Queensland, as well as New Guinea
HabitatMostly in the rainforest regions
Common PredatorsCat, kestrel, crow, foxes
Seasons active fromMostly during summer (march – July)
Host Plants Not recorded
Diet  of larvae and adultsLarvae: Decayed wood
Adults: Decayed wood, alongside sap, nectar, and fruit of their host plants
Rainbow Stag Beetle Picture

Identifying the Damage Caused by Them

Though they mostly feed on rotten wood and saps of trees, reports of their damage to the host plants remain unrecorded.

Did You Know

  • The two subspecies of this beetle include Phalacrognathus muelleri muelleri (Queensland), and Phalacrognathus muelleri fuscomicans (New Guinea).
  • Scottish naturalist and zoologist Sir William Macleay named it Phalacrognathus muelleri to honor the German-Australian physician, Baron Ferdinand von Muelle.
  • Their bright, vibrant coloration makes them an object of interest for beetle collectors, though the color eventually fades once they die.
  • Because of their long lifespan and less aggressive nature, these beetles make for great pets. They do well in households with kids since their not so large mandibles do not cause much harm even if they accidentally sting someone.

Image Source: i.pinimg.com, naturesface.com.au, jonathansjungleroadshow.co.uk, live.staticflickr.com, jonathansjungleroadshow.co.uk

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