Blackspotted pliers support beetle (Rhagium mordax)

Blackspotted Pliers Support Beetle (Rhagium mordax)

(also known simply as Black-spotted Longhorn Beetle)

The Blackspotted Pliers Support Beetle, Rhagium mordax, is a member of the longhorn beetle family (Cerambycidae), known for its long antennae and distinctive body shape. It is one of the more common and easily recognizable longhorn species in Europe’s forests.

🪲 Identification

• Length: 10–20 mm
• Shape: Elongated body with typical longhorn beetle shape
• Coloration:
  • Dark brown to black base color
  • Four pale yellow or whitish spots on each elytron (wing case), giving the “black-spotted” appearance
  • The spots are usually uneven and irregular in shape
• Antennae: Long, about half to full body length, often slightly shorter than in some other longhorn species

The contrasting pale spots on the dark background are the main distinguishing feature.

🌿 Habitat

• Prefers deciduous and mixed forests, but also found in:
  • Woodland edges
  • Parks
  • Hedgerows
• Often associated with fallen, decaying timber, especially broadleaf trees

🌱 Diet

Larvae:

• Feed on dead or decaying wood, especially:
  • Birch
  • Beech
  • Alder
  • Oak
• The larvae bore into wood, playing an important role in the decomposition and recycling of dead trees.

Adults:

• Occasionally feed on nectar or tree sap, but adults are mostly short-lived and focus on reproduction.

🔁 Life Cycle

• Eggs laid in cracks or under bark of dead or dying wood
• Larvae bore deeply into the wood, feeding and developing for up to 2–3 years
• Pupation occurs inside the wood
• Adults emerge in spring to early summer (typically May to July)
• Lifespan of adults: usually only a few weeks

🌍 Distribution

• Widely distributed across:
  • Europe
  • Central and northern Asia
  • Introduced in some regions outside its native range

🧬 Interesting Facts

• The name “pliers support beetle” refers to the shape of the adult beetle’s head and thorax, which somewhat resemble a set of old-fashioned pliers.
• Plays an important ecological role as a decomposer and a part of forest nutrient cycles.
• Frequently preyed upon by birds, small mammals, and predatory insects.

🛡️ Conservation Status

• Not threatened
• Common in many parts of its range, especially where old forests or deadwood habitats are preserved

The Blackspotted Pliers Support Beetle (Rhagium mordax) is a key species in forest ecosystems, contributing to the natural breakdown of wood and providing food for numerous predators. Its attractive, spotted pattern makes it one of the more easily recognizable longhorn beetles for insect enthusiasts.