- DEADLY fire ants are on the march across America after developing a
mutant strain that can survive winters. The ants, whose venom has killed
dozens of people in the southern states, also cause damage to crops, lawns
and electrical equipment estimated at £1.5 billion a year. In the
past, they could survive only in the humidity of the American south. Now
they are heading north.
- Their most recent victim was a woman
in a nursing home in Jackson, Mississippi who died in September after the
ants swarmed over her body, riddling her with stings.
- Children in the suburban south are regularly
stung. Most come away with a painful blister which subsides after a few
days. Two in every 100, however, need immediate hospital treatment or they
die. In the American south-east, the ants have overtaken wasps and bees
as the major source of allergic insect reactions.
- A hybrid strain that seems able to withstand
cold weather has now been found in California, far from the ants' traditional
areas, which stretch from Florida to Texas. The insects, whose mounds pop
up from the ground after rain, are believed to have crossed from South
America to Alabama in the early part of this century.
- They travel across country on livestock
or bundle into giant balls that can float down flooded rivers. After swarming
on to a human victim, they are believed to emit an alarm pheromone, at
which point they all sting at once, causing maximum pain. Most fatalities
occur in those who cannot escape: elderly people, babies in cribs or people
who suffer from dementia.
- Now scientists are commandeering the
ants' natural enemies from South America. They have imported a parasitic
fly that can wriggle inside the quarter-inch long ant and lay its egg.
When the larvae hatch, they move into the ant's head where they feed until
the head falls off. Faced with the fly, the normally fearless ant recoils
and races towards its mound.
- The scientists are also testing a micro-organism
that occurs naturally in Brazil, which, if implanted into a fire ant nest,
sickens the ants, slows their reproduction and causes the queen ant to
produce fewer eggs.