Species of the Month: October 2024

Silverfish: Lepisma saccharina

During 2024, our 20th anniversary year, we are revisiting our Species of the Month archive to reshare some of our "greatest hits" through the years. This month we are looking back to September 2015, and the ubiquitous Silverfish. At the time the species was incredibly under-recorded, with just 8 records in the SEWBReC area! Things have impoved, with records now standing at 98 (an increase of 1125%), but there is are sure to be many more sightings going unrecorded.

One major change since 2015 is the arrival of a potential confusion species, the Grey Silverfish (Ctenolepisma longicaudata), which currently has 2 records in Wales. This newly introduced species is larger and has a blotchy and hairy appearance, but is similar enough to make it worth taking a photograph to be certain of identification. You can find comparison photos from English Heritage here.

View the 10km distribution of Silverfish here (Wales)

View the 1km distribution of Silverfish here (SEWBReC).

Original text

Often considered a pest species, the humble Silverfish is associated with damp and cool locations, including basements, garages and bathrooms. Amazingly there are only 17 records of Silverfish in the WHOLE OF WALES [153 in 2024], 8 of which lie within SEWBReC [98 in 2024]. An excellent example of something considered too common to record!

This fast moving (and well named!) species is quite disctinctive, with its fishlike shape and silver colour. The only possible confusion species is the Firebrat (Thermobia domestica), but this similarly well named species is associated with warm locations such as bakeries, and is brown in colour. [see text above for information on new confusion species, Grey Silverfish]

A little more information on Silverfish is available from NatureSpot.

This map on Aderyn shows the distribution of Silverfish at a 10km square level for the whole of Wales. Zoom in or click on a 10km square to see the 1km square record distribution.

If you spot a Silverfish (or Firebrat!) during September (or see the species at any other time of year), please send us the record, ideally via SEWBReCORD or the LERC Wales App. Instructions on how to submit records are available here.