Invasive Species

Alert Species

Monitoring and controlling invasive species that have already become established in Britain is crucial. However, we must also always be aware of new, potentially invasive species that may be ‘on the horizon’. Be aware of the possibility of encountering the following species and follow the recording advice given on this page.

  • Quagga mussel (Dreissena bugensis rostriformis)
  • Asian hornet (Vespa velutina)
  • Killer shrimps (Dikerogammarus villosus and D. haemobaphes)
  • Water primrose (Ludwigia grandiflora)
  • Carpet sea-squirt (Didemnum vexillum)

Established Species

Identification of invasive species is the key to successful management and control.The following identification sheets have been produced by NNSS and are available for you to download for free.
Once you are sure of your identification, please help us by submitting your record.
Submit a Sighting

Some browsers or devices may not display this table correctly. If so, scroll to the bottom of this page for a simple list of species names.

Zebra Mussel
(Dreissena polymorpha)

Zebra Mussel
Alpine Newt
(Ichthyosaura alpestris)
Alpine Newt photo courtesy of Kat Cooper
Himalayan Balsam
(Impatiens glandulifera)

Himalayan Balsam
Orange Balsam
(Impatiens capensis)
ID sheet coming soon
Orange Balsam - Trevor Renals
Parrot’s Feather
(Myriophyllum aquaticum)

Parrot's Feather
Canadian and Nuttall’s Waterweed
(Elodea canadensis)
Canadian and Nuttall's waterweed
Curly Waterweed
(Lagarosiphon major)

Curly waterweed
New Zealand Pigmyweed
(Crassula helmsii)

New Zealand Pigmy weed

Large Flowered Waterweed
(Egeria densa)

Large Flowered Waterweed - Christian Peters (Plantlife)

Water Fern
(Azolla filiculoides)

Water Fern (c) GBNNS under cc
Hottentot Fig
(Carpobrotus edulis)
Hottentot Fig
Australian flatworm
(Australoplana sanguinea)

Australian Flatworm - Food and Environment Research Agency (Fera)
Quagga mussel
(Dreissena bugensis rostriformis)

Quagga Mussel - USGS
Chinese Mitten Crab
(Eriocheir sinensis)

Chinese Mitten Crab - GBNNSS
American Mink
(Mustela vison)

American Mink
Signal Crayfish
(Pacifastacus leniusculus)

Signal Crayfish

Submit a Sighting

Alphabetical Species List