The secretive snow flea

We tend to think of winter as a quieter time of year for wildlife, with so many creatures hiding away and sheltering from the cold. However, winter does offer opportunities for new species spots. RSPB Scotland's Species and Habitats Officer James Silvey tells us all about one of these creatures, the snow flea.

The secretive snow flea

Snow flea (Boreus hyemalis) Photo: Gilles San Martin

I’ve always loved winter. Short winter days bring the chance of seeing new species and the opportunity of catching up with old friends brought south to escape the extreme winter weather. Winter also brings with it challenges, and for me the challenge this winter is to see one of the UK’s toughest insects, the secretive and elusive, snow flea.

The snow flea or snow scorpionfly is a small insect (4-6mm) that confusingly is neither a flea or scorpionfly but is distantly related to both. The snow flea gets its name from its peculiar habit of emerging and being most active during winter, often seen walking across snow patches and jumping in small hops if disturbed.

Snow flea (Boreus hyemalis) Photo: Gilles San Martin

During mid-winter most of Scotland’s insects are hibernating yet the snow flea has an amazing adaptation to this extreme environment that enables it to remain active, anti-freeze blood. With this insect superpower, adults can spend the winter foraging for soil invertebrates or scavenging on the bodies of other insects that have succumbed to the cold without the threat of competition or predation from other invertebrates like spiders.

Snow flea on snow (Boreus hyemalis) Photo: Wikimedia Commons

The species is primarily found across the UK in areas such as moorland, woodland and bog habitats with good amounts of moss which the larvae feed on. Despite relatively few insects being active in winter these incredible animals are seldom seen with most records coming from eagle eyed folk who happen to see a metallic coloured insect walking across areas of snow from one mossy patch to another.

Because they can be found in such a wide range of habitats going out to see snow fleas can be tricky and most observations are simply pot luck. However, if you’re out walking this winter and notice that you’re walking through an area with lots of snow and moss patches then take a minute or two to look for the mighty snow flea, proudly braving the worst that the UK’s winters can throw at it.

The closely related Scorpion fly, Scotland (Photo: James Silvey)