Yes, there are midges in Singapore. They can cause a lot of problems. A patron of an eatery in Teban Gardens recounted her experience with midges in Singapore:
“It was a fine afternoon and I was sitting at the corner of a bustling eatery, trying to fill my stomach after a morning of hard work. Set lunch was the perfect choice for a hungry soul. However, when I was about to start the lunch break with a sip of soup, I found that a bug was taking a nice warm dip in the soup. ‘Maybe I’ll skip the soup and let you have it.’ I told myself, and the bug. I was about to dig in when a swarm of bugs invaded my personal space and turned my peaceful lunch break into a horrifying experience that I will never forget.”
You may hear similar stories from people who live or work near Pandan Reservoir where tiny insects known as midges give the residents and local authorities serious headaches. There are two main groups of midges in Singapore, namely biting midges and non-biting midges.
Biting midges are insects in the order Ceratopogonidae. They are more commonly known as sand flies and some call them “No-See-Ums”. Adult biting midges feed on blood so they leave painful bites on humans as well as other animals. On the other hand, as the name suggests, non-biting midges do not bite as the adults do not feed.
Habitat and Life Cycle
Non-biting midges are in the order Chironomidae which houses more than 10,000 species. Their life cycles are similar to that of mosquitoes and flies which undergo 4 developmental stages, namely egg, larval, pupal and adult stages.
Midges in Singapore can be found in stagnant or slow-flowing water bodies such as drains, ponds, lakes and water reservoir. Female midges lay eggs on water surface, in masses which contain up to 3000 eggs. After 2 to 3 days, the eggs sink to the bottom of water where they hatch into larvae. They feed on sediments and organic matters that are found at the bottom of the water.
The larvae of certain species are well-known as “bloodworms” which are used as bait or fish food. After 2 weeks of larval development, the midges spends 3 more days in the pupal stage before they emerge as adults. Adult midges do not feed and they spend the only 2 days of their lives entirely for mating and continuing the family line.
The high reproductive capability of midges causes a large number of eggs to be laid, and adults will emerge at the same time forming large swarms. Favourable conditions such as optimal temperature and the presence of ample food and breeding sites facilitate the emergence of large number of midges in Singapore during certain times of the year.
Mosquitoes vs Midges in Singapore
Midges are often mistaken as mosquitoes for their similar appearance. However, their differences can be recognised upon close examination. Firstly, as adult midges do not eat or drink, they do not possess proboscis. Proboscis is a needle-like mouthpart found on insects such as mosquitoes and butterflies that is used to suck liquids such as nectar and blood.
Another distinct physical appearance of midges is that their bodies are usually longer and more slender than that of mosquitoes. One of the most commonly found midges in Singapore has a distinct green coloured body. Unlike mosquitoes, midges do not transmit diseases and they are classified as nuisance pests.
How Do We Control Midges in Singapore?
Although non-biting midges are harmless and do not bite humans, a large number of them are a nuisance and can interfere with outdoor activities. It is almost impossible to eliminate them completely as they are part of nutrient rich aquatic habitats. However, tackling them using drastic measures are sufficient to control them under the threshold level. Controlling non-biting midges in Singapore can be divided into insecticidal, biological and physical controls.
The substantial number of non-biting midges present in Bedok and Pandan reservoirs of Singapore has led to the increase of fogging frequency to twice daily by PUB (Public Utilities Board). The reason for this is to target the most active time of non-biting midges in Singapore so that they will be interfered with the treated zone during their swarming activities.
Fogging is carried out as a “quick fix” solution to those flying adult non-biting midges. The chemical used is permethrin, which is certified and recognised by both WHO (World Health Organization) and NEA (National Environment Agency). Reservoir dykes, drains, and surrounding vegetation at Bedok and Pandan are the focal point for treatment as those are the breeding sources of midges in Singapore.
Biological approach of using Bti (Bacillus thuringiensis israelensis) larvicide to kill midge larvae is another environmentally friendly practice used by the government of Singapore. Bti is a naturally occurring bacterium in soil that is capable of producing toxins which only specify in targeting the larva of aquatic insects.
Hence, it is safe as it does not pose any risk and toxicity to humans and animals. More importantly, water quality is not affected by Bti application. PUB of Singapore is doing well in applying and increasing the dosage of Bti to the bottom of the reservoir to prevent the larvae from hatching into the adult stage.
On the other hand, inspection and removal of breeding sources are also carried out to reduce the midge population. The method: physical removal of midge eggs floating on the surface of the reservoir. A 3 metres high netting has been placed along the edges of the reservoir to prevent the adult midges from being blown from the reservoirs to the residential areas (midges are weak fliers, easily blown by wind).
Furthermore, to attract adult midges from keeping within the reservoirs, strong spotlights at pumping stations of reservoirs remain on from 7am to 7pm. Recently, thousands of fish, guppies, mollies and swordtails, were introduced and released into Pandan Reservoir. The strategy is to target the pupae of midge, which act as the prey of those released fish.
Controlling the population of midges in Singapore is not an easy challenge but we are certainly taking it on. With more research and knowledge about the insects, we will be able to come up with new innovative measures to keep their populations under check.