Garden slug varieties in Alberta

Several varieties of garden slugs have been documented in Alberta, with both introduced and native species found in gardens, agriculture, greenhouses, and nurseries^[1]. The most commonly reported and significant garden slug species in Alberta include:

• Deroceras reticulatum (grey field slug or netted slug): This is the most abundant pest slug species found in agricultural fields and is also common in gardens and greenhouses^[1].
• Arion fasciatus (orange-banded arion): Found in both greenhouses/nurseries and, more rarely, in residential gardens, this species is introduced and associated with plant material movement^[1].
• Arion hortensis (small black slug): An introduced European species occasionally recorded in Alberta, usually near horticultural operations^[1].
• Arion rufus (red slug): Introduced, found in greenhouses and nurseries^[1].
• Arion subfuscus (dusky slug): Introduced and recorded in Alberta, found mostly in greenhouse/nursery environments^[1].
• Ambigolimax valentianus (three-band garden slug or Lehmannia valentiana): Often associated with greenhouses and nurseries, and encountered in gardens^[1][2].
• Deroceras invadens: Synonymous with the invasive Deroceras panormitanum, found in Alberta's horticultural settings^[1].
• Deroceras laeve (marsh slug): This species is regarded as both native and introduced and can be found in diverse habitats including gardens and greenhouses^[1].
• Prophysaon andersonii (reticulated slug): A native slug species, less common but present in Alberta’s environment^[1].

Of these, the grey field slug (Deroceras reticulatum) and orange-banded arion (Arion fasciatus) are the primary pest species in home gardens, causing persistent plant damage^[1].

Other less common but occasionally reported slug species in Alberta (from surveys including parks, greenhouses, and garden donations) include:

• Limax maximus (great grey or leopard slug), which is large and rare in Alberta residential settings^[1][2].

Slugs in Alberta are most numerous and problematic in wet years or irrigated environments, with numbers peaking in mid to late summer^[1].

These pest slugs are typically introduced via the horticultural trade and plant material movement and can be difficult to eradicate once established^[1]. The native slugs are outnumbered by introduced species in garden and disturbed environments^[1].

Where possible, practices such as hand-picking slugs, reducing overwatering, and monitoring around plant-rich environments are recommended for management^[3].

The information above is based primarily on scientific surveys and agricultural reports on pest species in Alberta, which provide the most detailed and region-specific inventory of slug varieties^[1].

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• https://www.cambridge.org/core/journals/journal-of-helminthology/article/pestiferous-slugs-and-their-associated-nematodes-in-agricultural-fields-greenhouses-and-nurseries-in-alberta-canada/BC51F0B3025E3BDA1C01433073448402                
• https://horticultureforhomegardeners.ca/2022/04/26/slugs-and-snails-in-the-ornamental-garden/  
• https://www1.agric.gov.ab.ca/FILE/BackyardPestMgmt_vegetables.pdf