07 August 2009

Sandflies: the bane of our shores

Sandflies are the beasts I most dread on the shore. I fear them even more than mosquitos.

Why? Because I can't see or feel them when they bite. I only find out I've been attacked a few hours or a day later, when the bite marks itch ferociously. And continue to itch for weeks. Often turning into hideous ulcerating wounds that make people wonder if I have some sort of communicable disease.
This photo taken by James today is definitely of a sandfly. It was biting Chay Hoon, who patiently put up with the bite in the name of documentation. Tanah Merah is probably the most sandfly-infested shore that I've been to in Singapore in recent years.

What are sandflies?

According to Wikipedia, the term 'sandfly' is commonly applied to a wide range of species and families of annoying biting critters. But they are generally true flies (Order Dipteria) which includes the mosquito and our familiar houseflies.

Why do they bite us?
Like mosquitos, it is the female sandfly that bites us for the blood meal that she needs to make her eggs.

Are they dangerous?
Besides resulting in highly irritating bites, in some places, some kinds of sandflies can trasmit leishmaniasis or sandfly fever. So far, I've not heard of this happening in Singapore.

How to deal with bites?
Scratching is not a good idea. It just gets itchier (in my experience) and the wound bleeds, gets infected and it is STILL itchy.

What works for me is to heat the bite with hot water, as hot as I can stand without getting second degree burns. Do this as regularly possible and the itch goes away in a few days instead of a few weeks. Chay Hoon swears by the hair-dryer treatment. In the office when, obviously, I can't put a hand under a hot shower, I just get hot water in my mug, put a spoon in it and then put the hot spoon against the bite. Ah...wonderful relief. But try not to do this infront of colleagues, especially if the bite is in an odd place.

In fact, as a standard routine, I try to douse all exposed skin with hot hot water as soon as possible after a field trip.

People have shared on the net lots of other treatments that worked for them. Some are in the links below.

How to avoid being bitten?
Don't go to places where the sandflies hang out. Like shores and other damp places.

OK, but IF we want to go the shores then how?
In my personal experience, sandflies tend to be more plentiful near the high water mark and near sea walls. Out on the reef flats, seagrass areas and sand flats, they are less plentiful. Although when there is no wind, they seems to be able to get out to you no matter where you are. They do seem to swarm in numbers at sunrise and sunset, but I have been bitten at all times of the day. Windy conditions tend to be more fly-free. And some shores appear to have seasonal infestations of them, e.g., Chek Jawa.

My personal bite-minimization approach
(I find there is no way to get zero bites):
  • Cover all skin. I wear long pants, long sleeved shirt and bring a towel to cover the back of my neck. But they still inevitably get fingers and even the face.
  • Stay away from the high shore and sea walls. If I do have to work in these places, I wear my thin raincoat which has super long sleeves and a hood. I'd rather sweat than deal with the bites.
  • I don't apply repellent on field trips. They smell awful, they are sticky and get on all my gear. But mostly because they are toxic to marine life. And from the article below, it seems they are toxic to people too. I agree with sgkopi.com that the smell of repellent may actually attract the beasts.
Here's more links to Singapore experiences and antidotes to sandflies. Seems like any outdoor activity has a risk of sandfly bites.
  • Ubin by sgkopi.com which has a photo of a really badly bitten foot. Ouch, I feel for the victim.
  • Fishing Kaki Forum with experiences and remedies shared
  • ExpatSingapore with more remedies shared
Have a sandfly experience or remedy to share?
Just leave a comment on this post. Thanks!

Study warns of bug spray risk
Some levels of Deet may be toxic to nerves
Straits Times 7 Aug 09;
PARIS: One of the world's most common insect repellents acts on the central nervous system in the same way as some insecticides and nerve gases, according to a study released this week.

Moderate use of the chemical compound, called Deet, is most likely to be safe, the researchers say.

However, experiments on insects, as well as on enzymes extracted from mice and human neurons, showed for the first time that Deet can interfere with the proper functioning of the nervous system.

Researchers say that further studies are urgently needed to assess Deet's potential toxicity to humans, especially when combined with other chemical compounds.

The researchers' findings may also shed some light on the so-called 'Gulf War Syndrome', the name given to a complex and variable mix of neurological symptoms reported by tens of thousands of US military veterans who served in the first Gulf War against Iraq in 1990 and 1991.

Developed by US Department of Agriculture scientists just after World War II, Deet has been available as a bug repellent for more than five decades.

Sold in the form of lotions, creams and sprays in concentrations from 5 to 100 per cent, it has been widely used not just by weekend campers but as a front-line barrier against malaria, dengue fever and other mosquito-borne diseases.

Some 200 million people use Deet-based products every year, according to the study, published in the British-based open-access journal BMC Biology.

Scientists still do not know exactly how the compound works on blood-seeking insects. Some say it blocks the sensory neurons that would be titillated by a potential meal, while others hypothesise that bugs are simply put off by the smell.

More surprising still, there is relatively little research on the effects of Deet in humans.

'It has been used for many years, but there are recent studies now that show a potential toxicity,' said Dr Vincent Corbel, a researcher at the Institute for Development Research in Montpellier, France, and lead author of the study.

'What we have done is identify a neurological target for this compound,' he said.

In experiments, Dr Corbel and a team of scientists found that Deet causes a toxic build-up of acetylcholine (ACh), the most common neurotransmitter in the central nervous system, that ultimately prevents the transmission of signals across the neuron synapse.

A class of insecticides called carbamates, as well as the nerve gas, sarin, work in the same way, only the effects are stronger and last much longer.

Fortunately, Deet is 'reversible', meaning that its impact is short-lived. But further studies are needed to determine at what concentration the chemical compound may become dangerous to people, especially young children and pregnant women, said Dr Corbel.


Singapore has rules for repellents with Deet
Straits Times 7 Aug 09;
SINGAPORE requires repellents containing Deet to be registered with the National Environment Agency (NEA) under the control of vectors and pesticides Act.

The environment watchdog told The Straits Times that repellents used in local households contain Deet in concentrations varying from 7 per cent to 25 per cent. This falls within World Health Organisation (WHO) recommendations.

'Should the WHO revise its recommendations, NEA will study the revisions and make the necessary amendments to ensure the products are safe for public use,' it said.

The NEA also advises users to follow the instructions on the label when using a repellent.

Said Professor Hugo Van Bever, a senior consultant at the National University Hospital: 'The fact that some 200 million people use Deet-based products every year, and that no major side effects have been reported in the medical literature, indicates that it is at least relatively safe.

'However, to be sure, more studies are indicated...My advice: if you can live without it, do so.'



  1. Got bitten badly by sandflies in the early afternoon near the shores of Changi Beach. Used to think that sandflies bite during the dusk and dawn.Boy was I wrong. Anyway it itches like hell now all over the body since I was sunbathing..you can imagine I was literally bitten from head to toe.Went on the net to find out some home remedies for my sandfly bitten skin. Seems that vinegar works for the itching...must be apple cider vinegar (white not brown).Also acts as an antiseptic and helps with the healing process. Fingers crossed hope that my skin recovers from this nasty episode.

  2. Ouch, I feel your pain...err...itch. Hope the cider cure helps you to recover quickly! Thanks for dropping by to share the experience.

  3. I got bitten at Changi Beach too! All over my legs, itch like hell. Terrible. Don't stay in the shade, I guess the sand flies don't like the sun like me, so they are enjoying a good lunch with me under the shade.

  4. Oh dear, I feel for you. Thanks for the tip about shady situations!

  5. These pests also lurk on holiday shores like Tioman. There's nothing worse than discovering that after being bitten so many times years back when I was beach crazy as a child, I am now allergic to the bites of those things. Totally suffered in Tioman.

  6. my right leg was totally badly bitten by sandflies at pulau ubin :( and it itches like mad and then i realised it could be sandflies. I THOUGHT i had some disease cause it was ret spots in patches all over my leg. and it looks super horrible and itches so terribly. i am still finding ways to cure it ><

  7. Oh dear. So sorry to hear that. Try not to scratch it, apply hot water. Sandfly bites can be serious, don't wait until it's too late before seeing the doctor.

  8. I was at Changi Beach, near Car Park 6. Didn't even know I was bitten until the next day when the itch & red spots became prominent. The itch is truly unbearable-never been bitten by sand flies before. Best thing to do is NOT scratch, as scratching exponentially expands the bites to ugly bumps & even itchier! 'Green grass oil' & clove oil didn't work. Calamine lotion lasted about 2 hrs of comfort. Trying Repaid Skin Relief Cream, tolerable itch so far.

  9. Oh dear! So sorry to hear that pv. Yes, Changi Beach is really bad. Try bathing gently with hot water. It works for me. Hope you recover soon.

  10. Thanks. I just tried putting aloe vera gel-fresh from plant. You cut a leaf, rinse in water then remove outler layer, leaving the gel, cut to fit the area of bumps, then secure with a plaster or the like. Leave for as long as you can, 1-2 hrs. The bumps would reduce in size, and less itchy.

  11. Try on putting Tea Tree oil. It works for me and my family. For babies or kids, you do a mixture of olive oil and tea tree oil. 1 tablespoon of Olive Oil + 5 drops of Tea Tree Oil. Hope it helps!!!

  12. I stop at the toilet next to car park beside Changi Ferry Terminal to get water to wash my car in my shorts and tee. Have done it several times. This is the first time, I was bitten 55 times in my arms and legs without knowing until few hours later. It is itching like hell for 2 days. Tried vinegar, aple cider vinegar, baking soda and many creams for itch. baking soda paste give the fastest relieve for 2 to 3 hours.

  13. To avoid sandfly's bite, apply baby oil on the exposed area. It helps alot whenever I kayak I need to beach up on some isolated islands where there will be armies of sandflies.

  14. I was bitten by sandflies two weeks ago at east coast park. The itch was unbearable n I went to a GP. Was given a jab, pills n cloderm cream to apply, using hot boiling water on it whenever it starts to itch but to no avail. There are still those big red itchy lumps on my legs! Help!! Does anyone knows of a good remedy to cure these deadly bites??

  15. Oh dear! That sounds terrible. I'm so sorry to hear this. Well, I guess you are more sensitive to them than most people. Perhaps ask the GP for stronger medicine? Anti-histamines?

  16. I was bitten 2mths ago at changi beach too! Both my legs is covered with 30+ over red bumbs the next fee days. Calamine doesnt really relieve the itchyness. I went to 2 gp, first gave me neoderm (steroid) & it just reduces the size. Second gp gave me diprocel it actually shrink further & dried up leaving brown marks that i have to deal with, however its so depressing to see some grows back to be red & itch again. I don't understand why. Now going back to home remedies applying pure aloevera which seems to be slow! Some ppl says it can took 6-12mths to cure completedly. Sigh

  17. Oh dear! That sounds bad. Yes, these bites can last for months. I'm sure you'll be better eventually. Thanks for sharing your experience and hope you recover completely soon.

  18. I was bitten 30+ times this weekend at Trikora beach, Bintan. I made the mistake of lying on the sand at around 5pm, in the shade. I will never make this mistake again!! After 2 sleepless nights of scratching and frantic rubbing, I took MC and went to my GP. He prescribed me 'prednisolone'. It's a steroid and I got a 5 day course. By the end of the first day, the bites had calmed down completely and I now have no issues. He also gave me some antibiotic cream to prevent infection from broken bites. One thing I did do, before the pills kicked in, was to buy some tiger balm plasters. I was working from home, so every time a bite started to itch, i cut a small square of the plaster and popped it on the bite. It did work, but i looked crazy by the end of my work, covered in white patches! I also recommend calamine lotion with menthol too, for general soothing.

  19. Oh dear Mindy, sounds like you got bitten badly. So sorry to hear that. Thanks for sharing your 'cure' and hope it will help others face this same unfortunate circumstances.

  20. I got bitten my them over at St John's Island. I thought they were mosquitoes since I killed some. When I got back to mainland, the itch was so bad I went straight to see a doctor. I never knew it would hurt that bad...now I'm still nursing myself with some creams and home made remedies.

    1. So sorry to hear of your ordeal. Hope you'll be better soon! Thanks for sharing your story.

  21. I just got bitten really badly by sand flies (so the doctors say) about a week ago all over the calves, feet and ankle for both legs. I was at the Toa Payoh park at night with a bunch of my friends enjoying the night breeze. We had decided to sit down for a few moments and BAM I started feeling bites all over those areas. It took about a whole day before the itch got really bad. I've been having sleepless nights these past few days because I would wake up in the middle of the night and the itch would be so horrible that I cannot fall back to sleep. I went to the doc twice for meds. The meds from the first round only helped temporarily. When I finished the course, I found that the bites had become even bigger from what they had been, which resulted me in visiting the doc again for new meds yesterday. Really hope the new meds will work. Learnt my lesson and I'm never going back to that park or any other park again at night :(

  22. I'm so sorry to hear about your experience Natalie. Thanks for sharing it so we can all learn from it. Hope you get well soon!

  23. I've got some sandfly bites a week ago. Most probably from Botanical Gardens. Rashes only appear the next day. Lots and lots of it on my feets and knee and hands. Its crazy trying to endure the itch. Every single night. At the moment using Calamine lotion with menthol and hot showers. Its helps to ease a bit. Does anyone knows anything about soaking in hot salt water? I know its gonna be a long battle and i will do anything to get through this.

  24. Oh no! So sorry to hear about your bites! Hot water works for me, but if the bites continue to trouble you, you might want to visit your doctor? If you scroll through the previous comments, you can see some of the solutions others have found useful. All the best for a quick cure to the itches!

  25. 2 days ago went to Changi beach and guess what? Just went to see dr. hope it help. the swelling is about 3cm each 6 on my left leg 5 on my right leg!

  26. Oh No! So sorry to hear this Aaron. Hope it the doctor will prescribe some medication that helps.

  27. Just went to the doc and found out that I was bitten by sandfly. However, the bites were only found round my ankle/foot, and it can be really itchy that woke me up in the night, scratching my foot like a crazy woman. I was confused between whether the bites were from the sandfly or bed bugs (my room was bed bugs infested previously) as they were only shown after the night. After doing much research, I guess they were from sandfly as my bites have a small hole/wound compared to my previous experience with bed bugs. It's really tormenting as not only Ive to deal with the terrible itch, Im on medication now too. :( I got the bites from pasir ris beach (midsum*** bre***) Im really down on luck as my friends didnt get them.

  28. So sorry to hear about your bites. Hope you recover soon.

  29. Got my sandfly bites from redang in june. Taaras resort to b exact. Had only a few bumps on the day I left. Came back and all hell broke loose. There are over 70 bites in total..on my legs, back, tummy, arms..and a couple on the face.
    took anti his and applied cloderm for a few days but saw no improvement. went to see gp and was given a jab of burofen. That worked for 4 days. bumps started to subside. I was happy again.
    Then on the 5 day, they slow glowed red again. A relapse I thought.. Went to see another gp. Was given 7 day antibiotic course of Augmentin, Telfast tablets for the itch and neoderm to apply. Took the augmenting after meals and it gave me such terrible side effects like a pounding headache and nausea. So I took it in the middle of my meals instead which was much better for me. Apparently hot showers is a no no. Cold showers are recommended. Seems perspiration and humidity are also contributing factors for the bumps to active.
    Its been month now..Still those red bumps just would not go away..so frustrating.

    1. Oh dear! I'm so sorry to hear about your traumatic experience. Thank you for sharing it so others may learn how to deal with their bites. Hope you recover soonest!

  30. Hi! i had 20 over bites on both my left and right legs at Punggol Waterway recently. I also went to see GP and given antibiotic cream called 'Fucicort' and oral antibotic medication for a course of 5 days. The redness is reduced however i still feel the itchiness occasionally. Now i have to bear with the ugly brown spots left on my ankles and I felt really demoralised by them

  31. Oh dear! So sorry to hear about your bites. Glad to know you are recovering. The spots will hopefully fade away with time.

  32. I got 34 bites the last time I did field work at Pasir Ris Beach. Took over 2 weeks for the bites to heal and over a month for the dark spots left behind to disappear.

    Applied insect repellent the next few times and didn't get a single bite. Don't worry, my work didn't involve entering the water so the spray stayed on me.

    I didn't see any doctor or anything because I didn't know they were sandfly bites until I did more research after my bites took way longer to disappear than mosquito bites. Scratching is definitely not recommended.

  33. I'm suffering from 47bites now from Pasir Ris near DowTown East. I went to see doctor and had medicine for eat and apply but it gone worst so now I'm using traditional way to cure. I'm sharing here hope can help whoever been bitten by sandfly too. Doctor medicine which not works on me 1)Pobancort cream 2)Allertec for itch and allergy. The medication I'm using now 1)69powder 2)Melaleuca Oil . Note : Scratching is a Big No No for any itchy bites !!!

  34. Don't laugh at this but I tried tiger balm for the itch spots and it does give u tremendous relief! Each time it itches, just dab the tiger balm into the areas affected and it should stop itching! Still waiting for it to subside from the gruesome bites 3weeks ago. Anyone has remedies to prevent scarring?

  35. Thanks for the tip Celena! Hope your bites are getting better. Alas, I don't know any remedies for scarring aside from not scratching. Which is really hard, I know.

  36. I just came back from St John's and Lazarus Islands and have apparently brought home countless bites with me, keeping me up tonight. I thought they were mosquito bites but I didn't quite see any and thanks to your picture I did identify several of them landing on me. They probably had their feast without me realising. Was wearing my bikini at some point and now I wish I didn't. Tomorrow I will be going for an antioxidant trial session, which would include being in a heated room and I sure hope that helps to stop this crazy itch! Will update if it does... My empathy to all other itching friends, hang in there.



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