Arboriculture Students Hunt City’s Toxic Moths

Arboriculture students from Capel Manor College have been drafted in by the Forestry Commission to prevent the spread of a dangerous moth found in the UK.

Four level two students and one level three student from the Crystal Palace Park centre are taking part in a survey group aimed at tackling the Oak Processionary Moth; a breed which poses health risks to humans and animals and has recently been discovered in heavily populated areas of London.

The risks posed to human health by the species occur when they are in larvae state (caterpillar). Covered in toxic hairs, if the hairs are touched or even inhaled, they can cause severe allergic reactions or skin irritations including conjunctivitis and respiratory problems such as pharyngitis and asthma. The threat posed to animals, including cats and dogs, is even more severe. The discovery of the species in urban areas has caused the Forestry Commission to react by spraying the trees with a variety of chemicals as they attempt to prevent the moths from spreading to new areas.

The point of outbreak is understood to be the importation of trees from Holland to London for a new development of flats in 2008. Since then the moths have spread to areas across the capital and into neighbouring counties, most predominately found in areas of south and west London and Kent.

David Bernstein is the level three Arboriculture and Forestry student taking part in the survey. Having completed the first stage of the survey in the summer which identified hundreds of nests on trees which required spraying, he and his fellow students are about to embark on stage two to assess the impact that the spraying has had and whether the moths have been successfully contained from the surrounding areas.

However, David questioned the effectiveness of the spraying operation stating that the summer foliage on the trees would have provided great protection for the moths, and as the spraying was done from ground height, the surviving moths would have simply moved to higher ground. He also raised concerns about the use of chemicals although agreed that left-unchecked the moths would multiple creating significant problems for the surrounding ecosystem:

“The chemicals used to spray the moth are indiscriminate in who they affect so there will be a number of invertebrates who will also die as a result of the spraying. However, if left to spread they could cause significant problems for the trees themselves as they lose energy as they attempt to repair the de-foliating damage caused by the moths.

“There are also a number of variables that would impact on the effectiveness of the survey- the wind direction for example being one of them. As well as this, the equipment required to spray the nest is rather bulky, which restricted the team from going into dense wooded areas. Our only hope is to contain the moths with the trapping system which is being employed while we identify an effective way to remove them.”

At present there is no predator for the Oak Processionary Moth in this country. Although there has been some talk of introducing a predator, this would bring its own problems as seen in the case of the American Crayfish in the river systems. It has been suggested that the Forestry Commission may be considering restricting access to some woodlands until the situation is stabilised.

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