Comment by bamboozled | Hacker News Reader

Comment by bamboozled | Hacker News Reader

Maybe there is some truth to the fact mosquitoes can only thrive with access to still water?

I once visited Indonesia and stayed at this place which was essentially jungle. I thought I was going to get destroyed by mosquitoes and yes we did have nets etc, but I was surprised at the lack of mosquitoes when outside.

I spoke with the owner who me that he doesn't worry much about mosquito born illness because he ensures there is no still water anywhere near his place. He said the most dangerous place for this type of thing was near small cities and towns because lots of dirty still water is present in gutters and pot holes etc. These places are breeding grounds for things like dengue fever according to the locals.

I can't really verify how true this but anecdotally I had a similar experience when I lived in a city, we started to get a LOT of mosquitoes hanging around our yard during rainy season. I went outside and noticed that many peoples bike tarps had sagged and formed ponds which had tons of mosquitoes hanging around them. I remembered what I learned on my trip and cleared all the water away. I do think it helped.

Definitely not trying to state this stuff as fact, just thought it would be interesting to share.

It is certainly true that mosquitoes need still water to breed, their larvae being aquatic. Depending on the species, this can be anything from a pond to a tiny puddle or even a thimble-full of water in a bromeliad. The main requirement is that the water remain for about 5-7 days, the time it takes for the larvae to go from egg to mosquito, so in places where the water from a rainfall dries up faster than that you aren't going to get a lot of mosquitos. If there's no still water, some mosquitos will lay their eggs in (slowly) running water as well, but few of the larvae are likely to survive as running water is likely to have plenty of other life in it and pretty much everything else that moves in water loves to eat mosquito larvae.

In order to keep the window of time that their larvae need to develop a small as possible, the females try to give their offspring a head start in the form of highly concentrated protein... the source for which is your blood! The only time they bite is when they're "pregnant" with eggs (so only the females), otherwise adult mosquitos feed mostly on nectar.

> running water is likely to have plenty of other life in it

And still water isn't?

He's taking about animal life, not bacterial.

In Rivers there are likely fishes etc, that's not the case with still water, as it often goes bad really quickly unless there is a filter installed, which usually also introduces some oxygen into the water etc.

Another reason why Mosquitos usually only use still water is that the surface tension is necessary for them to inject their eggs, and moving water doesn't support their weight

Do you know if there are some rules to how fast the water should be? I know in siberia there are some rivers with suuuper slow speed, you almost can't see that it moves. I know that there are myriads of mosquitos too. Would be interesting to know if there's a connection to water speed and the amount of mosquitos breeding.

Significantly less macroscopic life. If it's a very small body it is likely to dry up eventually, so that rules out long-lived fully aquatic lifeforms. Even predatory insect larvae (for example, dragonfly larvae) have a much longer development cycle than mosquito larvae, so you won't find them in a body of water that will only be around for a few weeks. The other factor is oxygen... even a still pond that exists year around will have much lower oxygen levels than moving water, and that's a significant limiting factor for aquatic life. Mosquito larvae are air-breathers (they rest just under the surface and have a "snorkel" that breaks the surface to breathe) so they can live in almost completely hypoxic water so long as there is microbial life for them to eat.

No, a small puddle is not going to have fish in it that eat mosquito larvae

This is all pretty much true.

Currently in Singapore where the local government is quite strict on standing pools of water.

Very on top of it with a reactive-proactive system.

If there's a confirmed (1? 2?) case of dengue they will send officials door-to-door in a neighborhood to inspect the house/office for any standing pools of water. I've been inspected with some regularity.

Government will also spray mosquito smoke to help control populations. Separately, Indo has trialed a releasing a bunch of genetically engineered mosquitoes[0]

[0] https://edition.cnn.com/2021/06/10/health/dengue-modified-mo...

If you are "caught" with a standing pool of water, what is the recourse? They help you fix the problem? Or do you receive a punishment?

not sure! i've never been caught with one and couldn't find any info on escalations.

many public service things come with a warning then fine system (beginning of COVID, masks mandates were this), but no definite answer here.

For the first such offense, you only get a warning. For repeat offenses, the fines and jail time ramp up fast, up to 3 months in prison for a single puddle found on your property.

Counterpoint to - living in Singapore.

I'm in Singapore in a conda/apartment block where we currently have an outbreak of Dengue (spelling?) fever - 4/6 infections. As much as there is legislation to say - empty your buckets - its pretty ineffective when condo/apartment owners are pretty useless, having been told there are pools of water on the roof of the apartments. They just move to twice a week fogging (spraying fog into the bushes - of which we have no clue what chemicals they are using - DDT anyone?).

We haven't had any government officials come.

Pretty sure NEA also releases special mosquitoes, not sure if sterile males or wolbachia.

Mosquitos lay eggs in standing water and one of the major mitigation techniques is removing puddles (old tires, canoes turns upright, etc). The CDC even recommends this for prevention of West Nile (a mosquito born illness) https://www.cdc.gov/westnile/prevention/index.html

Last summer I put water into a basin (d~50cm) to create some humidity, which I believed was lacking in my room. The room is usually isolated from the outside and AC-ed due to the heat. Some day I noticed a mosquito and it successfully fed on my leg. Fast forward a week, I surprisingly started noticing more mosquitoes. That was unexpected because a couple may come in by chance, but something felt off to me then. In this semi-alarmed state I started to check around, when noticed the basin - it was full of t-shaped larvae, every few cm2 there was one. In disgust I washed it with best chemicals I had and never experimented with it again.

Idk if these larvae actually produced new mosquitoes or if it was just a coincidence.

There was no need to wash it with chemicals, the larvae would have just died after they went to your canalizations... Or just boiling water ?

I am surprised by the amount of people who think everything needs to be sterilized. They will use bleach to "clean" every surface and do not seem to understand the basic of how soap works....

Grease --> Soap, Hot water

Tart --> Boiling alcohol vinegar

Everything else -> Water, the best solvant on earth.

Yes I know basic chemistry, soap would do just fine. But I was under the affect of having spawning pool in my command center :)

This is effective for mosquitoes for two reasons

First, because they lay eggs in standing water. Second, because mosquitos are relatively weak flyers compared to other flies. They often only travel a few hundred yards from where they were born during their lifetime.

So removing standing water is an excellent way to keep mosquitos at bay. If you can't, applying BTI spores to the standing water can target their larva.

Reason 2 is also important. You can often avoid mosquitoes in any area if you're willing to deal with a few large fans.

Speaking from my experience kayaking, mosquitos are a tiny bit more frequent close to water than say in the middle of a forest, but not much. The real multiplying factor are swampy terrains, particularly close to places like water locks[1].

I've been told that the reason mosquitos are in bigger numbers in those places is that this is where they lay their eggs.

[1]: <https://en.wikipedia.org/wiki/Lock_(water_navigation)>

And on top of the standing water factor, a city is less likely to have the mosquito's predators. I'm from Wisconsin which has plentiful mosquitos, but there's a state park that has had an abundance of bat houses for many years, and there's practically no mosquitos in the park.

Standing water is required but not the only factor.

In Vietnam there is plenty of standing water in the cities but malaria is almost non-existent.

Go outside in the rural areas and malaria is more common. You not only need water but a reservoir of disease for the mosquitos to transmit.

It's Up To You: Dengue-Yellow Fever Control

https://archive.org/details/ItsUpToYouDengue-yellowFeverCont...

From my experience in Indonesia places with malaric mosquitoes are clearly marked and dealt with by local authorities.... Even on remote islands...

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