Defra, UK - Plant Health

Code of Practice to Prevent the Spread of Non-Indigenous Flatworms

About this Code

This Code is a practical guide to help producers and traders of nursery stock to detect and thereby to limit the spread of non-indigenous flatworms, notably the 'New Zealand' flatworm, Arthurdendyus triangulatus, and the 'Australian' flatworm, Australoplana sanguinea.

Although this Code of Practice has no legal force, demonstration of adherence to its provisions could be taken into account in the event of a case arising.

Under the Wildlife and Countryside Act 1981, it is an offence to release or allow to escape into the wild any animal which is included in Part I of Schedule 9 of the Act. This includes the New Zealand flatworm.

The Need for a Code

Non-indigenous flatworms prey on earthworms and so pose a potential threat to our native earthworm populations.
Further spread of non-indigenous flatworms could have an impact on wildlife species dependent on earthworms and could have a deleterious effect locally on soil structure.
Findings in some parts of the United Kingdom indicate that non-indigenous flatworms are becoming more widespread.
The principal means of spread is considered to be through movement of plant material and soil. By following hygienic practices and undertaking careful inspections of their stock of plants, nursery stock producers, garden centres and traders can help to limit the spread of flatworms.

In addition, because the New Zealand flatworm is known to occur in parts of the United Kingdom, certain countries which import UK planting material have expressed concern that they might import the flatworm.

By showing adherence to a Code which lays down monitoring and inspection practices, UK producers will be able to demonstrate that they are taking measures to avoid spreading the flatworm through trade in planting material both within and outside the U K. Failure to prevent the spread of flatworms could threaten UK exports.

Scope

This Code applies to plant producers, nurseries, wholesalers, garden centres and other retailers of plants and is directed at all stages of plant production and marketing.

Identification
The New Zealand flatworm	New Zealand Flatworm with blackcurrant-like egg capsule (4 -11mm long) (inset)
The New Zealand flatworm was probably first introduced to the United Kingdom some 40-50 years ago, and in certain areas – particularly cool and wet regions – it has become locally abundant and widespread, particularly in domestic gardens. It has gradually spread, most notably in Northern Ireland, Scotland and northern England. In England, findings have been mainly in domestic gardens and allotments, predominantly in northern counties, such as Tyne & Wear, Durham, Cumbria, the Wirral, Cheshire, Greater Manchester and West Yorkshire. There have been relatively few sightings in central or southern England and similarly, there is only a small number of records from Wales.

Australian Flatworm	The Australian flatworm
	The Australian flatworm appears to be a more recent introduction than the NZF, but is now quite widespread, particularly in SW and NW England. It was first recorded in the Isles of Scilly in 1980 and has since spread along the southern coast of Cornwall, Devon and Dorset, and into Hampshire. There is also a concentration of findings in north Wales and NW England (Clwyd, Merseyside, Cheshire and Greater Manchester). However, there have been very few findings from the east of the country and none from along the whole eastern coastline of England.
Flatworm egg capsules Flatworm egg capsules appear in the summer and resemble shiny smooth slightly flattened blackcurrants. They are between 4-11 mm long and 3-8 mm wide. Juvenile flatworms emerge after about a month and are creamy white/pink in colour.

Other creatures such as leeches or slow-worms have in the past been mistaken for flatworms, but careful examination should help avoid mistakes. There are also several native flatworms which are mostly small and inconspicuous (about 2cm). These pose no threat to the earthworm population and should be left alone.
Leech: tough body wall, with fine cross lines and a sucker at each end	Earthworm: thin, rounded, obviously segmented body
Kontikia – a small black flatworm Another non-native species, Kontikia ventrolineata, has been found at about six sites – allotments and domestic gardens – in Devon and Cornwall, and there are also records from Liverpool and Guernsey. Thought to be of Australasian origin, a recent record from Scotland indicates that it may be increasing in numbers and could be more widespread than current findings indicate. K. ventrolineata is reputedly able to feed on any small invertebrates that it can catch, including molluscs, and possibly slugs. It is much smaller than the Australian and New Zealand flatworms, measuring 1-2 cm in length. Oval or cylindrical in cross-section, it is very dark, almost black in colour, with two narrow lines (pale grey) running down the length of the body close to the midline. There are two native land flatworms (Microplana terrestris and Rhynchodemus sylvaticus) that are similar in size and colouration to Kontikia. However, both of these lack the longitudinal dorsal stripe.

Above two Kontikia photos taken by Mike Lole of ADAS