Common Pest Myths in Vietnam, Checked
Every country has its folk knowledge about pests, and Vietnam has a rich set of it. Some of it is sound, some is half right, and a few beliefs actively point people away from what would work.
Sorted here into three groups, with the reasoning rather than just the verdict.
True
Cockroaches come up through the drains. Correct for the large American cockroach, which lives in drainage systems and enters through dried floor traps. Not correct for the small German cockroach, which lives indoors and does not use drains at all. The half that is true is the half that matters most, because it points at the right fix.
Termites swarm after the first rains. Correct, and the flight indicates a mature colony nearby that has existed for years rather than something arriving.
Sealed containers stop weevils and moths. Correct, and it is the single most effective household measure against stored product pests, because they arrive inside packaging rather than entering from outside.
Partly true
A clean house does not get cockroaches. Cleaning slows a population and does not decide whether one starts. German cockroaches arrive in cardboard, in appliances and from adjoining units, and they can live on grease film in a void no cleaning routine reaches.
Camphor and naphthalene balls repel insects. They work in a sealed trunk where vapour concentration builds, and do almost nothing in a ventilated wardrobe. Against rodents they do nothing at all.
Dark clothing attracts mosquitoes. A small real effect at close range, dwarfed by carbon dioxide and body heat. Worth knowing and not worth changing your wardrobe for.
Simply wrong
Ultrasonic repellers work. Tested repeatedly against rodents, cockroaches, mosquitoes and ants over decades, with no meaningful effect. This is the most widely sold ineffective product in the category.
Bay leaves, cucumber and coffee grounds repel cockroaches. No useful effect on a population. Harmless, and they displace the measures that would work.
Mosquito-repelling plants clear a balcony. The oils repel when extracted and applied to skin. A plant in a pot releases almost nothing, and if it has a saucer under it the net effect is negative.
Vitamin B1 stops you being bitten. Tested and found to have no effect.
One cockroach means thousands. Depends entirely on species. One large drain-dwelling cockroach is usually a plumbing observation; one small striped one in a kitchen genuinely does suggest an established population.
The one that causes real harm
Spraying is the strongest response. An aerosol used broadly scatters a German cockroach population into new voids, disperses ants without touching the nest, spreads bed bugs through a property, and leaves repellent residue on exactly the surfaces where bait would go.
It is the belief that most reliably turns a contained problem into a distributed one, and it is the one worth abandoning first.
Two more are worth adding because they come up constantly. Rats are attracted to a dirty house. Partly true and misleading — rats are attracted to accessible food and shelter, and a tidy house with an open bin store next door and a gap under the door is a better proposition than an untidy one that is sealed. Bed bugs mean the place is unclean. Simply wrong, and one of the more damaging beliefs in this list, because it makes people slow to report and slow to seek help.
Why the myths persist
Pest populations fluctuate for reasons unconnected to anything anyone did — weather, season, what a neighbour is doing, a building repair. Anything adopted during a peak is followed by a decline, and the decline gets attributed to the measure.
That mechanism explains most of the enthusiastic reviews for products in the third group, and it is worth holding in mind about our own industry too. A monthly fogging contract that treats no source benefits from exactly the same effect.
Related reading
See things that do not work and do plants repel mosquitoes. On cleanliness, an honest answer. For species, the two cockroach species and the termite flight. Our parent company sets out its methods in Vietnamese at khutrungtoancau.vn.
Global Pest Control is the English-language arm of Khử Trùng Toàn Cầu, based in Thu Duc City.
Common questions
My neighbour swears by an ultrasonic device. Are they wrong?
About the device, yes, and about their experience, not necessarily. Pest activity varies with season, weather and what is happening in nearby buildings, so a decline after installing something is common and is not caused by it. It is worth being gentle about this — the belief is sincere and the underlying observation is real.
Is there any traditional method that genuinely works?
Several. Sealed containers for rice and flour, emptying and wiping water containers weekly, keeping floor traps filled, and a fan in a room where you are being bitten are all traditional, free and effective. The pattern is that the physical measures hold up well and the repellent substances mostly do not.
Why do pest control companies not correct these?
Some do. Others benefit from a customer who believes a monthly visible treatment is the answer, because that is an easier product to sell than sealing a gap once. It is worth judging a company partly by whether it tells you something is unnecessary, since a company that never does has no incentive to be accurate.
