Oak Processionary
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| Oak Processionary | ||||||||||||||
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 Oak Processionary caterpillars in nest on oak tree trunk
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| Thaumetopoea processionea Linnaeus, 1758 |
The Oak Processionary (Thaumetopoea processionea) is a moth whose caterpillars have come into conflict with humans both as pests of oak forests and because of the health hazard posed by their poisonous setae (hairs), which may cause skin irritation and asthma.
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[edit] Distribution
Oak processionary moths are widely distributed in central and southern Europe, but are occasionally found as far north as Sweden. In the southern countries of Europe the populations are controlled by natural predators, but these predators do not exist in northern Europe. Their range is expanding northward, possibly or partly as a result of global warming and they have already eroded some forests in the Netherlands. Since the summer of 2006 the moth has also arrived in areas in west London, and it is believed that this is because of the importation of oak from the Netherlands.
[edit] Description
The wingspan of adult stage moths is between 25 and 35 mm. Their pattern of tan, brown and white make the adults difficult to see against oak bark. Adults fly during July and August. The larvae construct communal nests of white silk from which they crawl at night in single file, head to tail in large processions to feed on foliage in the crowns of trees, later to return in the same manner.
[edit] Public Health Problem
The moths are posing an increasing threat to humans as their range is being extended by the warming European climate. The backs of older caterpillars (3rd to 6th instars) are covered with as many as 63,000 pointed defensive bristles containing an urticating toxin (thaumetopoein or closely related compounds). Even if the larvae are not handled, the setae break off readily, become airborne and can cause epidemic caterpillar dermatitis (lepidopterism), manifested as a papular rash, pruritus, conjunctivitis and, if inhaled, pharyngitis and respiratory distress including asthma or even anaphylaxis.
[edit] Control
[edit] England
Infestations of this caterpillar were first found in several locations in London in 2006. The general public have been asked to look out for these caterpillars and to report them, rather than deal with them themselves. The County Councils: Brent, Ealing, Hounslow and Richmond upon Thames have all set up their own task forces to deal with out breaks. Sightings of these caterpillars in other areas get reported to the Forestry Commission. [1] The research agency of the Forestry Commission has also issued guidance on the way to contain out breaks and deal with infestations, so as not to increase the risk to the public still further. [2]
An emergency amendment came into force on the 31st March 2008 which added the Oak Precessionary Moth to the list of pests in the The Plant Health (Forestry) Order 2005 and thus requiring all Oak trees coming into the UK from the rest of Europe, to have Plant Passports.[3]
[edit] Belgium
In 2007 infestations in the Belgian province of Limburg were so acute that governor Steve Stevaert deployed 20 soldiers to burn them[2].
[edit] References
- ^ The Forestry Commission. Oak processionary moth. Accessed 2008-05-31
- ^ Forest Research Survey and intervention in relation to different phases of the oak processionary moth life cycle. Accessed 2008-05-31
- ^ Office of Public Sector Information. Explanatory memorandum to the Plant Health (Forestry) (Amendment) Order 2008 No. 644.[1] Accessed 2008-05-31
- Maier, H. et al. (2003) British Journal of Dermatology 149(5):990-997, November.
[edit] External links
