Rove Beetle

By M.K. Lim,

     The Rove beetle that is increasingly common in Malaysia. Their bodies contain the toxin paederin (hence Paederous dermatitis) that causes burns on human skin whenever they are crushed. Interestingly the beetles were used to burn off warts in the past. It starts off with some erythema/redness and then with patches of ulceration where the beetle has been crushed.

Rove beetle

     The rove beetles are surprisingly small and very easy to miss. Normally they fly into your house via the windows as they are attracted to light at night. They can fly up apartment blocks and are common if you live near a hill or jungle.

     The Rove Beetle is less than 1 cm long. The body is dark orange and the tip of the abdomen, the upper abdomen and the head are black. The upper middle iridescent greenish region of the abdomen are the hard wings (elytra). A pair of transparent wings are neatly folded and hidden under the hard wings. During daytime, the beetle will be seen crawling around swiftly with hidden wings resembling ants. When disturbed it raises the abdomen in a threatening gesture like a scorpion and can fly away. It can also run on water swiftly.
 
      The beetle has been observed in the paddy fields (since 1919), school fields - within the grass etc. It is carnivorous and eats smaller insects. Thus it plays an important role as a biological control of ‘paddy pests’. During heavy rains/ floods, the beetle may migrate to drier areas.

Rove Beetle's wounds

     The haemolymph in the beetle’s entire body (except the wings) contains the most poisonous animal contact toxin in the world called ‘pederin’ (C24 H43 O9 N) named in 1953. It is 12 times more poisonous than cobra venom ! Dried and stored rove beetle for 8 years still retained it’s toxicity ! Contact collision with the beetle while travelling or sleeping, crushing it on the body or smearing with soiled fingers can cause conjunctivitis and severe dermatitis known as dermatitis linearis, paederus (rove beetle /staphylinidae) dermatitis, whiplash dermatitis etc. In September 2002 an epidemic of dermatitis linearis caused by rove beetles affected thousands of high rise flat dwellers and dormitory students in Penang, Malaysia.

     Since the beetle is attracted to lights at night, switch off or minimise the lighting and close doors/ windows during the beetle epidemic. Use fine mosquito netting, aerosol insect spray, glue traps etc. Do not sit near lights, do not smash the beetle on the body, just blow it away ! If there is contact with the beetle, immediately wash the affected area with soap and water. Those who suffer severe skin reactions should seek medical attention.