The ‘Cape Mountain Rifles’ Beetle


The CMR bean beetle (Milabris Oculata) is a large, conspicuously coloured beetle in the family Meloidae (blister beetles) that is frequently seen all over the Lowveld. ‘CMR’ refers to the Cape Mounted Rifles, a military unit in the old Cape Colony whose uniforms sported black and yellow bands that resemble the colours of this specific beetle. Blister beetles are, of course, well known for their chemical defences, primarily cantharidin (the active ingredient in ‘Spanish Fly’, an extract from a European species of blister beetle). This compound is a painful irritant, especially when in contact with mucous-lined membranes such as those of the gastrointestinal and urinary tracts. Blister beetles emit body fluids containing cantharidin from joints on the legs when disturbed, giving any would-be predators a foul-tasting appetizer. This can cause blisters when in contact with skin and may even be fatal if ingested, both to humans and livestock. Insects with such effective defences are often brightly coloured to advertise the fact that they are poisonous, foul-smelling or distasteful. CMR beetles are not only just a frustration for potential predators and other animals but also a serious pest for numerous fruit and vegetable crops – large numbers of adults congregate on plants and feed on the flowers. After mating, the female lays her eggs in the ground and the larvae of this beetle, after hatching, feed on grasshopper eggs, while the adults feed on flowers for the most part. They are slow-flying insects, and the adults are most often seen between late spring and early autumn. CMR bean beetles have very few specific habitat requirements and occur in almost every corner of South Africa.

Ranger report by Kaden, Images by Andi