The Curious case of the ‘Rat Effect’ in Hanoi


At the height of Empire, France deployed administrators, engineers and technocrats to develop, modernise and control Southeast Asia. Following the alarming work by Alexandre Yersin in 1894, who discovered the role of rats and fleas as vectors in the propagation of bubonic plague which still held a profound cultural legacy in western Europe, the colonial state became increasingly concerned about the presence of rats in their cities. Nowhere more so than Vietnams Hanoi did rats become the focus of the colonial states attention.

At this point it is worth noting the contribution of the German Economist Horst Siebert with his ‘Cobra Effect’, in short the ‘cobra effect’ is when an attempted solution to a problem only exacerbates the issue and makes it worse. The French Colonials in Vietnam and their rats are a case book example, above and beyond that provided by British Colonials in Delhi.

Legacy fear of plague became enflamed when the symbols of progress and order lavished upon the wealthy European section in Hanoi, such as sewers and flushing toilets, became a wide-ranging underground transportation network for rats and the ideal breeding ground. The officials decided that rats popping out from a Europeans toilet would simply not do, this lead to what Historian Michael Vann calls ‘The Great Hanoi Rat Massacre’.

The colonial regime created a bounty programme that paid entrepreneurial locals for each rat killed, tails were used to count kills. As time passed Colonial officials began to notice rats with no tails in Hanoi…further investigation releveling a network of emergent rat farms, with tails removed and rats freed to continue to breed and pump life into the new lucrative sector of Hanois economy.

Case book cobra effect. Where French colonial officials had tried to solve the rat problem in Hanoi they underestimated the intelligence and imagination of the residents, the problem had simply increased (less a few tails).

Cockroaches, Bed Bugs, Fleas, Mice and Rats: The conditions of the UK’s worst Asylum Housing.

The Oxford English dictionary defines Asylum as protection and shelter from danger granted by a state to someone who has left their home country as a political refugee, the provision of such being an obligation every stable civilised state should accommodate. However, the Home Affairs Committee has called on the conditions of some asylum accommodation a “disgrace”, infestations include rats, mice, bed bugs, fleas and cockroaches. Pests present a risk both to an individual’s mental wellbeing alongside their physical health.  One resident’s flashbacks to the cell where he was detained and tortured should send chills down our spine and firm our resolution to act.

Reports of mice and rats scurrying across kitchen tables, urine soaked carpets, insect ridden beds, all raise a point of concern from those within the Pest Control industry who are aware of the risks associated with a lack of control.

The Government has said it is committed to “safe, habitable” accommodation, yet it seems like there is a disregard for the risks of Hantavirus, Leptospirosis, Rat-Bite Fever, Salmonellosis, LCMV and Murine Typhus to name but a few. Our obligation to ‘shelter from danger’, seems to come with mixed interpretations on what is classed as a ‘danger’.

The elderly and young are most at risk to the bacteria and viruses carried by rodents, but also those with weakened immune systems. When we look at the diets and the conditions from which many asylum seekers come, it is clear that the bulk part of those granted Asylum in the UK can be grouped into the ‘at risk’ category. It is not only the risks to health, but the risk of structural damage to the accommodation itself which can incur substantial costs. This should be taken seriously when there are far more pressing things to finance over damage and associated costs for a matter which is preventable.

John Whitwam, Managing Director for Immigration at G4S says “isolated examples of poor practice” were not a reliable guide to the standards most asylum seekers receive. While this might be a set of isolated examples and not reflective of all accommodation, it is never the less reflective of irresponsibility on the part of the property management team.

One of the increasing strains on the provision of pest control for councils and indeed the private sector, is the ever rising cost of professional technicians. This is where the market has the solution. Amateur use pest control will solve pest issues, empowering those in the accommodation to take responsibility for the hygiene of their abode and offers a monumental cost saving to local councils. In turn, the tax payer by removing the labour cost. Food for thought.


By Olivia Hunt

Consider your colours carefully if you don’t want the bugs to bite !

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If you are using red or black beddings, you may want to reconsider your choice of colours.

Bed bugs (Cimex lectularius) are a parasite of man, feeding and surviving on blood. Bed bugs like to hide in cracks and crevices.

Bed bugs are becoming increasingly resistant to insecticides, which prompted scientists to try and define what would make the perfect harbourage for these blood sucking creatures.

Researchers at the University of Florida and Union College decided to see if bed bugs showed any color preferences.Bed bugs were placed in the middle of petri dishes with different colour shelters made out of card and a 10 minute slot was allocated to each bug to choose a hiding spot. The color choices were shuffled around to cover different dish locations and the experiment was carried out amongst a wide range of bed bugs, with different age, sex and feeding habits. Females who were about to lay eggs were also part of the experiment to see if they had a favourite shade under which to leave their brood. The bugs’ choices were subsequently recorded.

The bugs appeared to show a preference for black and red, whilst they appeared to dislike yellow and green shelters.

You may originally think that these tiny creatures prefer red because it is the colour of blood, their 1st choice meal, but it may also be because bed bugs themselves appear red as adults and the little bugs simply like to go to these harbourages in order to meet up with their bug mates.Alternatively, it could also that red and black being dark colours, they represent a safe hiding place away from well lit areas, where bedbugs don’t like to hang out.

These findings are not conclusive as not enough research has been done. However, it gives us an indication of which colour could be used with a trap system for an effective way of getting rid of the little monsters.


By Myriam Clark

3 Formidable Predatory Insects

Assassin bug

Assassin bugs are among nature’s most ingenious killers, although are harmless to man but do have excruciatingly painful bites. There are many species of assassin bug, they often specialise in a certain kind of prey; for example, some of them feed only on spiders, others prefer ants, etc. They kill their prey by shooting their needle-like mouth parts inassbugCPBclose2to the body of their prey and inject in their lethal saliva, which liquefies the victim’s innards. They are pretty formidable in their attack; however, most assassin bugs are not fast runners or flyers so they have come up ingenious ways of trickery in their hunting tactics. Some cover them cover their bodies in bark, dust or even dead insects to disguise their appearance and scent, and sneak up on unsuspecting prey. Spider-hunting assassin bugs mimic vibrations produced by insects tapped in their web, fooling the spider into thinking they have caught an insect, to only be killed and eaten themselves. Possibly the most remarkable assassin bug is the species which feeds on ants. It secretes a sugary substance through its abdomen, which acts as bait for the ants, but it is loaded with a powerful tranquilizer. Within seconds after ingestion, the ant collapses, paralyzed, and the assassin bug can suck its innards without any resistance.


Japanese hornets

Japanese Hornets, known as ‘Tiger Hornets’ in some parts of Asia, are large wasps and relentless hunters that kill any insects they can capture. In their armoury, they have an incredibly potent venom and have the ability to inject great amounts of it and repeatedly inject this venom. Their venom is so potent it will cause serious illness to humans and can even cause death, they are classed as the most dangerous animal in Japan – killing around 40 people per year (more than bears and snakes combined). The Japanese Hornet uses its sting only as a defence mechanism; to kill prey, it uses its sharp jaws to decapitate the victim, and cut its body in small pieces. It then carries the carcass back to the nest to feed to the larvae. Follow the feeding, the larvae produce a sweet sugary liquid which is the adult hornet’s primary food source. Japanese Hornets, in groups up to 10, have been known to completely devastate a honey bee colony in a couple of hours, decapitating every single bee in the nest (up to 30,000) one by one. Once the bees have all been killed, the hornets feed on the honey and carry the bee’s larvae back to their own nest to heed the larvae. The Japanese Hornet, a truly formidable predator.



The Dragonfly is the ultimate aerial killer of the insect world; its design is so perfect, that it has remdragonfly-lead.jpg.653x0_q80_crop-smartained almost unchanged for the last 300 million years. It is one of the fastest flying insects to have ever graced the skies and can reach speeds up to 56 mph which, if you consider the size and fragility of a dragonfly, it is rather astonishing. It can dive-bomb, hover like a helicopter, and even fly backwards, and its enormous eyes, which cover almost all of its head, give it near-360-degree vision, so that no insect escapes its attention. Dragonflies will feed on any insects they can catch, also spiders which they capture straight from their webs. Although they usually hunt and devour prey at high speed in the air, they can also snatch spiders and insects from exposed surfaces. Not only are the Dragonflies formidable predators, their larvae are also daunting predators; they use their protractile, sharp mouth parts to stab other small animals to death, including small fish, frogs and other dragonfly larvae.

By Lee Silson

3 Insects that belong in the alien world

Devil’s Flower Mantis Idolomantis Diabolica5587004-lg

One of the strangest and largest praying mantis of all, which is saying a lot when talking about praying mantids. The female can measure up to 13 cm in length and develop a range of natural colours, that allows them to mimic the Devil’s flower, a type of orchid. Mantids are predators and their hunting style involves sitting motionless and waiting for their pray to come within reach. They then whip their arms out and snag their pray – usually flies, beetles and in some cases birds. They use their colours to mimic flowers to lure their pray to within reach.



I can honestly say this is one of the oddest-looking creatures I have ever laid eyes upon. The ‘stinger’ at the back of the insect is not a stinger at all and is something much more innocuous: the fly’s genitals. Scorpionflies can be found all over the world and have been around scorpionflyMesozoic age and they are believed to have been the forerunners of most of our modern moths and butterflies, collectively grouped in the Lepidoptera order.


Pipevine Swallowtail Caterpillar

The Pipevine Swallowtail is a beautiful fluorescent blue butterfly which is commonly found in North and Central America. However, its larvae are an Screen-Shot-2013-03-10-at-5.37.21-PMarmoured congealed-blood-red caterpillar which have tinted visor shades for eyes and a quadruple row of blunt horns running across its body. These caterpillars live in groups when young and as they grow older they wander off on their own before entering the chrysalis stage. Certainly, a strange looking larva.



Written by Lee J Silson