International Starch: Snail Pest Control

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International Starch Institute
Science Park Aarhus, Denmark
Slug pest - Arion lusitanicus Mabille 1868

Third Generation Electrical Fence

Arion lusitanicus Mabille 1868 is considered a major slug pest of European agriculture. This pest originated in south-western Europe at the Iberian peninsula. It has now spread as far north as Scandinavia. In Denmark the first specimen was found in 1991. In the United States it has not spread yet, but it was found at Cornell University in October 1998 and has been reported as far away as the Falkland Islands. The slug is not specific in its food requirements but is considered a pest of a wide range of vegetable crops in Europe - including the potato as the natural insecticide 'solanine' is not effective against the snail.

The Latin name "Arion lusitanicus" is still the name used in English speaking countries, which are not yet plagued, but in continental Europe it has even nicknames. In Denmark:"Iberisk skovsnegl", "Iberiaskovsnegl", "Den spanske skovsnegl", "Dræbersnegl". In Sweden: "Den Spanska skogsnigeln", "Mördarsnigeln". In Norway: "Iberiaskogsnegl", "Mordersnegl". In Holland: "Spaanse wegslak". In Germany: "Kapuzinerschnecke", "Die Spanische Wegschnecke".

Arion lusitanicus is a night slug - hiding under vegetation, in dark and moist places, during the day. It is most easily observed in the twilight. The colour is everything from dark brown over reddish to yellowish colours. It is a naked snail and looks like its black cousin 'Arion ater' and the red 'Arion rufus', from which it cannot be distinguished without microscopy. Length: 7-15 cm; Crawling speed: 5-9 m/h. Occurrence: Unto fifty snails per square meter. In plagued gardens 20 to 100 snails may be collected per day. If a reddish brown snail is observed in large numbers most probably Arion lusitanicus is at work.

A questionnaire distributed August 2000 in a residential district encircled by green space studded with snails revealed, however, little or no interest in doing something serious about it but complaining. Some spaces, however, are so infected, that the slugs are driving residents mad. Other researchers report annoyed people ready to move.

July 2002 the Danish Ministry of Environment declared war against the snails. The snails create headlines in the media.

Slug control. Traditional poison and deterrents may be used, but in the case of Arion lusitanicus the chemicals have to be replaced after rain because of massive immigration from adjacent green areas. Traps and manual collection are measures to keep down the number. A copper tape (not tested) looks attractive because it may have a lasting deterrent effect and even better if the copper tape is turned into an electric fence by connecting an energiser.

The pictures below show a prototype of an effective electric fence connected to a one joule energiser
(A research initiative by International Starch Institute).
Picture left: An Arion lusitanicus is approaching and about to touch the electric fence and
Picture right: one second later it has been neutralised.
Potential manufacturers may apply for a licence.

Attack1.jpg (46003 bytes) defeat1.jpg (28310 bytes)

Slug and snail control:

Sodium iron EDTA www.farmwide.com.au/nff/vetasscn/infoshet/snail.htm Advertised as a safer alternative to the metaldehyde and methiocarb-based slug and snail baits.

Iron phosphate. www.biconet.com/crawlers/sluggo.html After eating the bait, slugs and snails will stop feeding, become less mobile and begin to die within three to six days.

Salt acts by extracting water.

Copper barrier tape: www.greenfire.net/hot/P350.html http://consep.com/consepold/hlg/slugsnal.htm www.duraplex.com/Snail.htm When slugs or snails contact the copper barrier a small electrical charge is released, repelling the beast. It lasts 3-5 years. Approx. retail price 1½-2 USD/m.

A beer trap: www.thetinpot.co.uk/slug.html Bury a tuna can up to its rim and fill it with stale beer. Keep it emptied by checking it for bodies each morning.

Slug and snail bait: www.bugspray.com/catalog/products/page177.html

Poison: www.homeandgardensolutions.com/products/products-spec-rfs-ss.html

Nematodes (Phasmarhabditis hermaphrodita): The effect on Arion lusitanicus is doubtful. Supplier of "Nemaslog": "Organic Gardening", Coomelands House, Addlestone, Surrey, KT15 1HY, England.

Diatomaceous earth: www.bugstore.com/slug.html dries out slugs just like salt, but doesn't add salinity to your garden.

Metaldehyde: www.laters.com/labels/slugliqu.htm Kill slugs which contact this material by crawling over sprayed surfaces. It does not have to be eaten as in the case of bait.

Copper sulphate - effect like metaldehyde.

Electric fence with energiser: www.poda.dk/nyheder/nyhed.htm#Dræberhegn Retail price: ~10 USD/m + energizer ~150 USD

Metallic fence with a 6 cm 55^o downwards sloping head is difficult to pass because the snail will drop off the bend. Information: "Borregaard Bioplant" +45 8678 6988.

Improved electric fence with under-crawling protective guard. Estimated retail price of one US$ per m and additional one hundred US$ for an optional energiser. Licensee wanted.

Slug control: http://www.oxalis.co.uk/slug.htm

Slug wars: http://eesc.orst.edu/agcomwebfile/magazine/97winter/text/OAPW9704.html#anchor371702

Slugs: http://www.greensmiths.com/slugs.htm

Snails and slugs: http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7427.html

Slugs! What can you do about them: http://www.cat.org.uk/information/tipsheets/slugs.html

German: Schnecken im Garten - Alles über die umweltgemäße Schneckenbekämpfung: http://www.ubavie.gv.at/umweltregister/sachinfo/schnecken/schneck1.htm

Danish: Bekæmpelse af dræbersneglen: http://www.faktalink.dk/eksemple/eksemple/draeb.fak/draebbek.htm

Keywords:pest,electric,fence,snail,potato,arion,lusitanicus,slug,control