Subject: Afghan Beetle
Location: Bagram, Afghanistan
August 23, 2016 4:06 pm
Hey. I wondered if you could tell me what this bug was that I caught crawling past my feet in the office when I had no shoes on! I’m sure he means no harm but didn’t want any nasty surprises crawling up my leg so I caught him anyway. I’ve let him go outside now though but still wondering what he was as he looks quite cool!
Signature: Dean, AFG
Your pretty beetle is a Ground Beetle in the family Carabidae, and we believe we have correctly identified it as Pheropsophus catoirei, a member of the subfamily Brachininae according to the Carabidae of the World site. According to BugGuide, Brachininae is the subfamily that includes Bombardier Beetles, a group that have chemical defenses explained on BugGuide as: “Adults have chemical defenses, ejecting toxic, foul-smelling gases from their abdomen with a loud popping sound. The explosive brew is composed of hydrogen peroxide, hydroquinone, and catalytic enzymes.” A very similar looking beetle is pictured on RevolvY where it states: “Bombardier beetles are ground beetles (Carabidae) in the tribes Brachinini, Paussini, Ozaenini, or Metriini—more than 500 species altogether—which are most notable for the defense mechanism that gives them their name: when disturbed, they eject a hot noxious chemical spray from the tip of their abdomen with a popping sound. The spray is produced from a reaction between two chemical compounds, hydroquinone and hydrogen peroxide, which are stored in two reservoirs in the beetle’s abdomen. When the aqueous solution of hydroquinones and hydrogen peroxide reaches the vestibule, catalysts facilitate the decomposition of the hydrogen peroxide and the oxidation of the hydroquinone. Heat from the reaction brings the mixture to near the boiling point of water and produces gas that drives the ejection. The damage caused can be fatal to attacking insects. Some bombardier beetles can direct the spray over a wide range of directions.”