Caterpillar that can kill is spreading over Britain

By DAVID DERBYSHIRE

Last updated at 12:03 14 June 2007


A potentially deadly caterpillar - whose bristles can trigger asthma and allergic reactions - has arrived in Britain from the Continent.

Nests of oak processionary caterpillars have been spotted in dozens of trees in London

over the last few weeks.

The discoveries have prompted fears that the species - normally found in the Mediterranean - has settled in the UK for good.

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The creatures first appeared in

Britain last summer after they

were brought into the country on

trees imported from Holland.

They are covered in 63,000

poisonous hairs which can trigger

allergic reactions and

conjunctivitis if they are touched. Even if they

are not handled, the bristles can

break off and be carried in the air. If

inhaled, they can trigger asthma.

In extreme cases, they can even

trigger anaphylactic shock.

The caterpillars normally live in

southern and central Europe, but have been moving north in recent

years as the climate has warmed.

In Europe, they cause a few

deaths every year through severe

allergic reactions to the toxin they

produce.

However, doctors pointed out the

creatures are probably no more

dangerous than wasps or bees.

Staff at Kew Gardens in West

London found and destroyed three

nests in their grounds last year.

This year, the number shot up to

40.

Kew’s head of trees, Tony

Kirkham, said: "We are dealing with

them as we find them, but I think

this is now something we will have

to be doing every year.

"The only

way they will be eradicated is if we

have a really cold, wet winter."

Kew insisted that the caterpillars

pose no threat to visitors or

staff, but it is urging gardeners to

report any more sightings to local

environmental health officers.

Although spraying kills them, the

caterpillars release thousands of

hairs as they fall to the ground.

The presence of these hairs - and

the fact that the toxin in them can

survive for up to a year - means

the risks remain even after the

caterpillars are destroyed.

Last year, officials at Kew were

forced to use hairspray to stick the

nests together before burning

them with blowtorches.

The caterpillars hatch in April and

do not pupate until June or early

July.

They have a grey body and

dark head with a dark stripe

running down the middle of the back

and a whitish line on each side.

They are covered in clumps of

long white hairs along the length of

the body, and shorter poisonous

bristles.

Oak processionary caterpillars

are so called because they emerge

in single file in long lines at night to

feed off leaves.

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