Myth or miracle? - Using 1-cent coins to destroy mosquito eggs

The following email about using the Singapore 1-cent coin (another version uses the Malaysian equivalent) to stop mosquito breeding has been circulating around. At first glance, this appears unrelated to water quality but read on... and find out another aspect of water quality and macroinvertebrates (bugs) that we seldom think about. (The common theme is about how clean water is indicated by a healthy bug community while polluted water is often dominated by the "uglies" such as leeches, tubifex worms.)

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Subject: How to prevent mosquitoes lay eggs, cheapest way of preventing survival of mosquitoes.


We cannot stop mosquitoes laying eggs at any stagnant water in drains/ponds or water collected in waste pails, tanks, tins, used tyres etc. etc. Of course if you have fish inside the tanks/containers then there should be no problem.


Do you know that there is a very simple and very economical way to destroy the mosquitoes' eggs and not let them hatch into larvae. Very very simple, just put in few 1 cent copper coins into the tanks/containers then it will solve all your problems.. Because in accordance to Japanese Research Scientists, they found the mosquitoes eggs will be destroyed by a kind of mineral discharge from the copper.


DON'T BELIEVE, Try it by yourself and even the small snails also will not visit the containers (with copper coins) collected with stagnant water. You will observe the water collected in the containers will be very clean and clear.
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Should you save up your 1-cent coins to keep the mozzies away? (By the way, production of 1-cent coins has been discontinued some years back due to inflation.) Here's my take:

Certain heavy metals (e.g. copper, lead) have been known to be toxic to bugs and their larvae in water (selected ref: 1, 2). These heavy metals exert their toxicity when they are dissolved in water at concentrations as low as below 1ppm (part per million).


The Singapore 1-cent coin is made of zinc plated over by copper according to the Singapore Mint. Solid copper is barely soluble in water but under certain conditions (e.g. acidity), significant amounts of the copper plating can dissolve into solution. With a sufficient concentration of dissolved copper in water, mosquito larvae (or eggs which are usually more vulnerable) can be killed.

Is the water then safe for drinking? It depends on the final concentration of dissolved copper. WHO (World Health Organisation) provided a maximum limit of 2ppm (2004 guideline) of copper in drinking water. But pouring the water into the sewers should not pose a problem.

Myth or miracle? Neither, it is science. No harm trying but I wouldn't count on this method as my only defence against mosquito breeding.

You can also read my interview on this topic in Lianhe Wanbao (4 Mar 10).