Snow Flea

Contrary to its name, the Snow Flea (Boreus hyemalis), isn’t actually a flea! It is in fact a type of flightless scorpion-fly (order Mecoptera). As you can see in the picture, the Snow Flea has a very long, downward projecting ‘beak’, which has biting mouthparts at the end – this is characteristic of scorpion-flies.

It can be found as an adult in the winter, when temperatures can make it too cold to fly, and lives among moss. Being active at this time of year affords the Snow Flea an advantage, as it can forage for food with a reduced threat of competition or predation.
Snow Fleas crawl and jump, rather than needing wings. The male’s wings are actually modified into curved spines used in mating and female Snow Fleas have wings so short, they’re barely visible. Females also have a distinctive curved ovipositor (which insects use to deposit eggs) that has an orange tinge.

They also have extraordinary jumping capabilities! Exactly, how the Snow Flea manages to jump up to 5 cm without muscular hind legs remains a mystery. Their build is rather dumpy and unlike the narrow body of a true scorpion-fly.

The Snow Flea avoids the mild south-west of Britain, preferring areas with a harsher winter (from Kent to Scotland). It seems to prefer sandy soils, as it is often found in heathland districts. However, it is rarely seen, mainly because people are not searching moss or snow in mid-winter and also because of its size, which can make it difficult to spot if you’re not looking for it. They present a great challenge for the keen naturalist!

• Size: 3-5mm
• Life span: Annual
• Diet: Eats moss and small soil invertebrates. Their larva is also predatory.
• Reproduction: Adults are active from October to April and during this time, mating takes place. The larvae withdraw to channels in the soil under moss around September to pupate.
• When to see: Adults are active October to April. You will find in moss or crawling/jumping over snow.
• Population Trend: Widespread in Britain but uncommon or under recorded.
• Threats: Climate change, which will cause warmer winters.
• Interesting Fact: The Snow Flea can jump up to 5 cm high, that’s 10 times its own size! This is thought to be a defence mechanism against predators.

How you can help:

Think you’ve spotted a Snow Flea whilst out and about? Join a recording scheme and log your finds – download the iRecord app and get recording!

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