Forestry chiefs and moth experts are working to determine the status of the pine-tree lappet moth following the discovery of a number of them in Scottish woodlands.
The species had not previously been recorded in Scotland, so it might be a previously overlooked resident, or a recent arrival.
Forestry Commission investigators and amateur moth recorders have discovered about 100 of the moths in five woodlands west of Inverness in recent weeks, including Forestry Commission Scotland's Boblainy Forest. The investigations were prompted by the discovery of a small number in the area last year, following discoveries of one in 2004 and two in 2007, which were not reported to the Commission at the time. Only males have been found so far.
The pine-tree lappet (Dendrolimus pini) is a native of Europe, Russia and Asia, where the caterpillars feed primarily on Scots pine needles. The moth was previously only known in Great Britain from a handful of sightings of individual males in southern England, which are believed to have been migrants from Europe.
The Commission is concerned that it could become a pest in this country. Its populations can increase significantly in parts of its range in Europe, usually after the occurrence of certain environmental factors, in particular very hot summers and dry winters. These periodic outbreaks can leave large areas of pine woodland stripped of foliage as the caterpillars feed on the needles. Many of the trees can die during severe outbreaks because the defoliated trees become susceptible to diseases, bark beetles and wood-boring insects as a consequence.
Roddie Burgess, head of the Commission's Plant Health Service, explained,
"We are carrying out urgent research to determine whether there is a breeding population and, if so, how long it might have been there.
"If there is an established population, we need to consider early action to prevent this species spreading further afield and potentially causing serious damage to our woodland environment and forest industries.
“We have not yet been able to determine the source of the moths, but different scenarios are being investigated. It is possible that they were brought in on imported pine trees, or in association with wood products or wood packaging. However, the localised nature of the finds so far suggests this is improbable.
"Accidental or deliberate release is another avenue that is always looked at in situations like this, and cannot be ruled out.”
Whether native or not, Butterfly Conservation Scotland (BCS) believes there is a possibility that the species will not be troublesome in Scotland. Dr Tom Prescott, species conservation officer, explained,
“We believe that the evidence indicates that pine-tree lappet is very unlikely to become a pest species in Scotland, primarily due to our oceanic climate and consequent wet winters and cool, wet summers.
"The species might already have been present as a breeding population for at least five years, and no damage has been seen or reported and no caterpillars have been found. It also has several natural enemies, including bats, birds, ants, fungi and parasitic flies and wasps.
"The moth has been discovered in a very under-recorded part of Scotland, where very little moth recording has taken place. It is, therefore, possible that it might be an overlooked resident species.”
The Forestry Commission, Scottish Natural Heritage and Butterfly Conservation are working together to investigate the source and monitor the sites to determine the size, extent and status of the population in the Inverness area. The partners are also exploring how populations of the moth might develop in Scotland's changing climate, and will continue to discuss proposed actions based on these findings and climate predictions.
Anyone who thinks they have seen a pine-tree lappet should contact Forestry Commission Scotland, by email to fcscotland@forestry.gsi.gov.uk or by telephone to 0131 314 6156, giving as precise a description of the location as possible - an Ordnance Survey grid reference is ideal.
Further information about the pine-tree lappet, including frequently asked questions, is available from the plant health pages of the Forestry Commission's website, www.forestry.gov.uk/planthealth.
NOTES TO EDITOR:
- Pine-tree lappet is a large moth: the males have a a wingspan of about 60mm (2.5 inches), while the females are larger at 80mm (3.2 inches). Males are a greyish or reddish brown with a white central spot in the middle of the wing with a jagged-edged band across the wing.
- Outbreaks of pine-tree lappet occur in parts of Europe. In years of peak activity they can result in seriously reduced tree growth, tree decline and tree deaths, especially because trees defoliated by this species become susceptible to other risks such as diseases, bark beetles and wood-boring insects as a consequence.
- Pine-tree lappet has many natural predators on the Continent. Bats feed on the adults, and birds are known to feed on all stages. Ants and parasitic flies and wasps feed on the caterpillars, and pathogenic fungi attack the caterpillars during their hibernation.
- Pine-tree lappet's preferred host is Scots pine (Pinus sylvestris). However, it is also known to feed on other conifer species, including Sitka spruce (Picea sitchensis), Douglas fir (Pseudotsuga menziesii), larch (Larix spp.) and lodgepole pine (Pinus contorta). All of these species are grown commercially in Scotland.
- Scotland's forests are estimated to be worth £800 million a year in products and services such as timber, venison, tourism, recreation and other benefits. A high proportion of Scotland's forest area is dominated by the species of trees preferred by pine-tree lappet, so if it does become a pest there could be a significant risk to jobs and businesses, particularly in economically fragile rural areas.
- Forestry Commission Scotland serves as the Scottish Government's forestry directorate, and manages 667,000 hectares of public forest land for multiple benefits, including sustainable timber production, nature conservation, public recreation, and rural and community development. For further information visit www.forestry.gov.uk/scotland.
- Scottish Natural Heritage is the Scottish Government’s advisor on nature and landscape, working to help people understand, value and enjoy Scotland’s nature. For further information visit www.snh.org.uk
- Butterfly Conservation is a UK charity taking action to save butterflies and moths. Its staff and volunteers manage habitats to ensure their survival, with particular attention to threatened species. It has 14,000 members (about 800 in Scotland), and is the largest organisation of its kind in Europe. For further information visit www.butterfly-conservation.org.
Media contacts:
- Forestry Commission - Charlton Clark, 0131 314 6500;
- Butterfly Conservation - Dr Tom Prescott, 01540 661469;
- Scottish Natural Heritage - Fergus MacNeill, 01463 725021.