What is a sandfly in Singapore, really? The final low-down.

(This article is originally published in the Entomologist Lounge, 1st February 2018)

We all talk about sandflies. Those seemingly invisible blood suckers that roam the sandy shores of Singapore, from East Coast Park to Coney Island and Chek Jawa. Their presence is unknown until they deliver painful bites and then they disappear into thin air, leaving behind those red bumps that last very long and itch endlessly.

Trying to understand sandflies is like trying to uncover the mythical Bukit Timah Monkey Man. People give different accounts on how sandflies look like. Misinformation are rife on the Internet. As helpful as the intention is, many local forums and messaging boards confuse Singapore sandflies with either New Zealand sandflies or black flies. Commercial pest management websites in Singapore have limited information. Not many official publications about Singapore’s sandfly species are readily available online for general public reference.

It is time we finally learn about our local sandflies! The Entomologist Lounge hits the library.

How does a sandfly get its name?

“Sandfly” is a common name given to many species of biting insects that is not a mosquito from Diptera order (the order that includes house flies, fruit flies, sewage flies, flesh flies, mosquitoes and midges). As different region names different biting insects as sandflies, this causes great confusion to many people who scour all over Internet trying to find out more about the “not-mosquito” that bites them. Here in Singapore, sandflies are known to bite humans at damp, sandy coastlines, hence its name.

Click here to learn more about blackflies, the often-confused cousins of sandflies in Singapore.

Alright, since common name is unreliable, what is the scientific name of sandflies (in Singapore)?

According to Singapore Biodiversity encyclopaedia [1], sandflies belong to family Ceratopogonidae, out of which 34 species have been recorded in Singapore from three genera (Culicoides, Stilobezzia and Dasyhelea).

It is the Culicoides species (also known as a biting midge ) that bites us on beaches and sandy coastlines in Singapore.

Singapore Biodiversity: An Encyclopaedia of the Natural Environment & Sustainable Development (2011).

How does a Culicoides sandfly/biting midge look like?

Picture does say a thousand of words when it comes to describing how a Culicoides sandfly looks like. The best way to describe a Culicoides sandfly is that it looks like a cross between a fly and a mosquito with spotted wings.

A close-up image of a Culicoides example during blood feed. Source: Agricultural Research Service (public domain).

The adult measures just about 1 to 4 mm in length. It is tiny, very tiny. So tiny that it makes a mosquito (about 10 mm in length) look like a giant next to it. That probably explains why we find it very hard to notice a sandfly until it is too late.

Size representation of a sandfly/biting midge (left) and a mosquito (right) feeding on a human skin. Source: Wikimedia (Author: Dunpharlain)

Note that there is no official photographic image of Singapore’s Culicoides species available at time of publishing.

But I read from Internet that sandflies can cause some scary disease called leishmaniasis. Should I freak out?

Leishmaniasis (also known as kala azar) is a disease caused by a type of protozoan parasite. It exhibits in form of ulcers on skin with fever, enlarged spleen and anaemia. Find out more about leishmaniasis here.

Despite of no record on endemic transmission within Singapore, there have been cases of patients, both Singaporeans and foreigners, who travelled from countries where leishmaniasis is endemic [2][3][4].

Another interesting fact is that leishmaniasis is transmitted by Phlebotomus and Lutzomyia species (from different family called Psychodidae), not Culicoides species we have in Singapore (from family Ceratopogonidae).

It is probably easier to associate those Psychodidae sandflies with Alfred Hitchcock’s movie Psycho.

Alfred Hitchcock’s Psycho (1960) film poster. Source: Horror Wiki (link)

Do we have Phlebotomus or Lutzomyia sandflies in Singapore then?

While Lutzomyia sandflies are not documented in Singapore, Phlebotomus sandflies are found in limestone caves in the Malaysian Peninsula. Out of six Phlebotomus species recorded, one of them (Phlebotomus argentipes) is a known vector for leishmaniasis in other parts of the world but there is no endemic case recorded in Malaysia. You can read about this study here.

This is how Phlebotomus and Lutzomyia sandflies look like.

Female Phlebotomus argentipes feeding on a human arm. Source: Ray Wilson (link)

Female Lutzomyia longipalpis feeding on a human arm. Source: Ray Wilson (link)

Both Phlebotomus and Lutzomyia sandflies have hairy mosquito-like appearance and may look similar between the two to an untrained eye without microscopic assistance. However, when compared to Culicoides biting midges, the difference in appearance between these two groups is more apparent.

Even though there is no record of Phlebotomus and Lutzomyia sandflies in Singapore, Singapore is only a hop across the Johor Strait to Malaysia, where Phlebotomus sandflies are recorded. With high traffic of foreign employees and travellers from endemic countries to both Malaysia and Singapore, and in between, it is important for governments to monitor for pre-emptive prevention and containment of introduced leishmaniasis.

Yikes! What can I do about sandflies/biting midges then?

To find out more what you can do about these blood suckers, click here for in-depth tips for prevention.

© Jo-Lynn Teh, BCE

Jo-Lynn Teh is ESA Board Certified Entomologist based in Singapore. While her specialisation is on tropical insects that affect public health and agriculture, Jo-Lynn’s passion is also to help people understand insects. Find her on LinkedIn.

Citations:

1. Ng, P. K., Corlett, R., & Tan, H. (2011). Singapore Biodiversity: An Encyclopaedia of the Natural Environment and Sustainable Development. Singapore: Editions Didier Millet in association with Raffles Museum of Biodiversity Research.

2. Tan, H. H., Wong, S. S., & Ong, B. H. (2000). Cutaneous Leishmaniasis: A Report of Two Cases Seen at a Tertiary Dermatological Centre in Singapore. Singapore Medical Journal, 41(4), 179-181.

3. Abraham, G., Leo, Y. S., Singh, M., & Wong, S. Y. (1997). A case report of visceral leishmaniasis in Singapore. Annals Academy of Medicine Singapore, 26(5), 713-716.

4. Tan, B. H., Lam, M. S., & Wong, S. Y. (1997). Three new cases of leishmaniasis: implications for the Singapore medical community. Annals Academy of Medicine Singapore, 26(5), 717-720.