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Benoit Martha

Streaked bombardier beetle (Brachinus sclopeta) © Benoit Martha

Streaked bombardier beetle

Benoit Martha

Fast facts

  • Latin name: Brachinus sclopeta
  • Notable feature: Armed with a powerful spray to deter and kill predators
  • Rarity in UK: Rare / Common
  • Where in the UK: East London, Margate

The Streaked bombardier beetle (Brachinus sclopeta) is so rare in the UK that it was only recently accepted as native and listed as a Biodiversity Action Plan species, meaning it requires conservation.

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It is one of only two bombardier species found in the UK, the other being the similar looking Common Bombardier (Brachinus crepitans) which despite its name is also rare. Like all of the 250 species of bombardier beetles globally, the Streaked bombardiers possess a remarkable but effective defence mechanism. It can spray a boiling, noxious chemical mixture of hydroquinones and hydrogen peroxide from the tip of its flexible abdomen, which it can aim skilfully, producing an audible explosive ‘pfut’ sound! This boiling spray has the potential to kill other insects and strongly deter larger predators, as well as curious humans!

The Common and Streaked bombardier beetles have a metallic blue - green wing case (elytra) with a narrow orange-red head and back (thorax), but the Streaked bombardier has a distinctive red dash along its back and is up to 7.5mm long.

Footage of a Bombardier beetle (though unfortunately not the Streaked bombardier), including their amazing defensive spray!

Where does it live?

Until the 21st century, the only confirmed records for the species were from Margate, Kent in 1830 and Beachy Head, East Sussex in 1928, leaving it as presumed to be extinct in the country for over 75 years. However, in 2006 a colony was discovered in a brownfield site near the Thames Barrier that was due to be developed. This prompted the 2007 translocation of the colony to a specially prepared recipient site nearby, consisting of rubble, crushed brick and concrete. In all, 61 beetles were found in the piles of rubble, plants and metal and re-homed, but it isn’t yet known how successful this project has been.

Then in 2010 a single female was found 3.5 miles north-west of the original site, in Mile End Park, during routine invertebrate monitoring. This suggests other populations of the Streaked Bombardier Beetle may be found in the large areas of brownfield habitat found in East London. As it stands, the Streaked bombardier is one of our rarest insects, known only from the lost Thames Barrier site near London’s busy City Airport and a tiny section of Mile End Park.

Little is known of the ecology of Streaked bombardier beetles, although it is thought that the larvae feed on Amara ground beetles. They favour the Thames area due to its strong estuarine character, depending on the warm, dry conditions as they are at the northern limit of their natural range. Like so many species in the Thames area, they depend on the thin soils, rubble and bare ground found in its brownfield sites. This makes protecting brownfield sites in the Thames area incredibly important, to make sure we can keep this wonderful beetle as part of the UK fauna.

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