Rove Beetles (Aka Tomcats) in Bali

You get up with some marks that feel and appear like a burn, however you don’t have any recollection getting them. Welcome to one among Bali’s greatest mysteries (which we’re completely happy to unravel for you).

Tomcat beetle on a leaf

Tomcat beetle on a leaf

Tomcats in Bali

First allow us to introduce you to paederus riparius, in any other case know because the Tomcat – an insect you’ll most likely by no means even see however will know in case you’ve been close to one because of its toxin which is stronger than cobra venom. These guys belong to the insect order Coleoptera (beetles) and the household Staphylinidae (rove beetles). Grownup Tomcats beetles are fairly small: 7-10mm lengthy and 0.5-1mm extensive (so across the measurement of a giant ant). For one thing so toxic, they give the impression of being innocuous with their black head, decrease stomach, and elytral (construction overlaying the wings) and a pink thorax and higher stomach. 1,4 Not all Rove Beetles trigger the pores and skin irritation we affiliate with Tomcats – that’s the specialty of the species belonging to the subfamily Paederini – of which Tomcats are a member.

Rove beetles are discovered in lots of nations and wish to stay in moist habitats, which can clarify why they’re followers of Bali’s rice paddies.1,4 The beetles are generally seen within the wet season or after significantly scorching and humid climate.3,7

Throughout the daytime, these beetles could be seen crawling round on the bottom, with their wings hidden and might be simply mistaken for ants. Grownup Rove Beetles are predators of different bugs. At evening they’re steadily discovered round gentle sources, which implies they typically inadvertently come into contact with people.1,2,4

tomcat burns

Burns on the again from secondary publicity to Tomcat Beetle venom

Tomcat Burns

Tomcat beetles are members of the subset of Rove Beetles with the poisonous venom which causes paederus dermatitis attributable to their extremely poisonous venom. Tomcats don’t chew or sting, however unintended brushing towards it or crushing it close to the pores and skin provokes the discharge of its coelomic fluid, which incorporates paederin, a powerful blistering chemical.1,2,4 Even utilizing a towel, or sleeping on a sheet which the beetle has been involved with can result in burns. Paederin has been in comparison with cobra venom, however it’s really the product of Pseudomonas micro organism dwelling as an endosymbiont inside the beetle.4 In any case, even a small publicity to this toxin may cause pores and skin and eye irritations.

If not instantly washed off, the chemical results in the attribute linear lesions with a burning sensation, reddening of the pores and skin, adopted by painful irritation and itching, with in depth pustules and blistering of the pores and skin, then heal with publish inflammatory hyperpigmentation.2,5,6,7 These indicators seem after 24-48 hours after contact and take every week, months, (or extra) to vanish.


Stopping human-beetle contact is the first technique of stopping paederine-based trauma. Above all else, in case you see a Tomcat, don’t deal with or dealing with or crush it. Blow or wash beetles off your pores and skin, and if it is advisable to exterminate, use spray with chemical insecticide spray then sweep them up and get rid of them. When you’re in an space liable to the beetles, minimise outside lighting at evening, as this can entice them.

Most people who find themselves burned by Tomcats in Bali discover they by no means see the Tomcat that offers them the burn, nevertheless, in case you’re in an space with a recognized downside, taking different insect-smart precautions can’t harm:

  • Put on long-sleeved and long-legged clothes to minimise uncovered pores and skin. Hold doorways closed and put screens on doorways.
  • Sleep underneath a mattress internet (this may occasionally cut back the chance of a beetle falling on the pores and skin through the evening).
  • Have bottles of soapy water useful for first assist. Use the buddy system to maintain a lookout for beetles on others.
  • Examine areas for beetles (particularly on partitions and ceiling across the gentle) earlier than going to mattress.
  • Clear extra vegetation from and across the residence, as beetles could relaxation in these areas.

Keep in mind that beetles may cause signs, alive or useless so at all times keep away from dealing with the beetle straight.


If a Tomcat is by chance crushed towards the pores and skin, instantly wash the affected space with soapy water. This may also help because the toxin penetrates the pores and skin slowly. Washing shortly after publicity will take away a lot of the toxin earlier than it has time to hurt the pores and skin. Afterwards, use chilly moist compresses, adopted by oral antihistamines and topical steroid (e.g. Hydrocortisone, Betamethasone) mixed with antibiotic (e.g. neomycin sulphate) ointments are useful towards pores and skin irritation and secondary infections.1,2,3,4,6,7 Watch out with treating the pores and skin irritations, as some conventional treatments can really make the marks worse. All the time search medical consideration for any extreme pores and skin reactions to the toxin.

Paederus beetle publicity is irritating and typically painful however could be managed extra successfully if individuals know the supply of the marks. Schooling and prevention are our greatest bets in coping with this tiny menace.

1. Singh G, Ali SY. Paederus dermatitis. Indian J Dermatol Venereol Leprol. 2007;73:13-5.
2. Mammino J. Paederus Dermatitis: An Outbreak on a Medical Mission Boat in The Amazon. J Clin Aesthet Dermatol. 2011 Nov:4(11):44-46.
3. Beaulieu AB, Irish SR. Summary: Literature evaluation of the causes, remedy, and prevention of dermatitis linearis. J of Journey Medication. 2016 July:23(4).
4. Gibbs LM. Watch out for the Beetle: A Case Report of Extreme Vesicating Dermatitis. Mil Med. 2015 Dec; 180(12):e1293-5.
5. Cáceres L, et al. Dermatitis Resulting from Paederus Colombinus: Report of an Epidemic Outbreak of 68 Instances within the Province of Darien, Panama. Cureus. 2017 Apr 12; 9(4):e1158. Epub 2017 Apr 12.
6. Mittal, et al. A Examine of Beetle Dermatitis. Indian J of Scientific Apply. 2013 Apr;23(11):714 – 716.
7. Karthikeyan Okay, Kumar A. Paederus dermatitis. Indian J Dermatol Venereol Leprol 2017;83:424-31.

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