Numbers of oak processional caterpillars (Thaumetopoea processionea Linnaeus) have grown to record levels due to the unseasonably warm weather the region has witnessed during spring, experts say.
The area effected by the infestation has grown dramatically since last year, encompassing most of the Limburg region, including the towns of Bree and Meeuwen.
Their numbers are now thought to be in the (m) millions.
The hairs on the back of the caterpillars are toxic to humans, causing anything from mild itching (akin to a stinging nettle) to painful irritations, asthma attacks and possibly death.
In the countryside outside the town of Bree, 140 kilometres (87 miles) from Brussels, local council workers were using naked gas flames to burn the caterpillars from the oak trees, the only tree they inhabit.
Using fire serves the double purpose of killing the caterpillars and destroying their hairs.
Council workers dressed in protective clothing and masks were using cranes to access the higher branches of the trees.
According to Ernest Essess, a Lieutenant at Bree fire station, the worst-case scenario is that a person inhaling the hairs "can go into shock and it can become life threatening"
Although no cases of extreme reactions have yet been reported, local authorities in the Limburg region of Belgium are taking no risks and are working to eradicate the caterpillars as swiftly as possible.
Officials say that due to a genetic mutation that occurred some 100 years ago, the caterpillars are immune to anti-pest spays usually favoured by authorities in such cases.
First sighted in 1758 in the Netherlands, the caterpillars have slowly spread southwards, feeding on oak leaves and nothing else.
The caterpillars' hairs, some 700-thousand on each animal, are millimetres thin and can be carried airborne by the slightest gust of wind. The caterpillars can also shoot their hairs off into the wind if they feel threatened.
Next week, 22 soldiers from nearby Leopoldsburg will be drafted into the area to assist in the disposal operation. officials said.
At the nearby Beckenbroek stud farm, the horses have also been feeling the effects of caterpillar hairs.
Of the 250 horses on the farm, some 50 have been affected. The stings soon get aggravated by the constant scratching and biting of the horses.
Starsky, a 10-year-old gelding horse, is no exception.
Due to his discomfort, the stable hands at Beckenbroek have been forced to put a specialist blanket all over him to protect him from the caterpillar hairs.