Butterfly watching in January?

, 17 January 2024
Butterfly watching in January?
Brown Hairstreak © Ryan Greaves

Bob Foreman

Biodiversity Data Specialist SxBRC

Of all Britain's 59 (there or thereabouts) species of butterfly, one of the most elusive is the Brown Hairstreak - even when you know where to find them, they're not easy to spot. For a start they are a bit of a rarity and in the UK mainly distributed in the southern counties, but they also spend most of their time resting on leaves high up in trees or shrubs, only occasionally coming down to nectar on flowers such as Hemp Agrimony and Common Fleabane.

Common Fleabane © Roger Wilmshurst
Common Fleabane © Roger Wilmshurst

Luckily Woods Mill is a bit of a hot-spot for the species and, in late July or August, it isn't too difficult to find them here (I managed to see about half a dozen last year). However, the very best time of year to find Brown Hairstreaks is mid-winter! Not the adults, but the eggs. These are tiny, brilliant white pinpricks, laid at the base of the thorns on Blackthorn (the preferred larval foodplant) stems and once you get your eye in, are quite easy to spot. The females lay their eggs in late summer, but it isn’t until the following spring that the tiny larva hatches and starts to feed inside the growing leaf-buds of the Blackthorn.

Brown Hairstreak egg © Bob Foreman
Brown Hairstreak egg © Bob Foreman

Winter can be a long, tough time, and we reckon, finding signs of the delights of summer to come is good for the soul!

Leave a comment


  • Wendy Allen:

    Great information, thank you. It helps one to observe the smallest things which one could easily pass without knowing.

    25 Jan 2024 13:07:00

  • Tim Joy.:

    That little butterfly is so beautiful. Is that one egg? Or is it a load of eggs in one bunch?! I’ll try find some. Cheers

    25 Jan 2024 16:41:00

  • Sussex Wildlife Trust:

    It is one egg. They are very small.

  • Kate:

    So interesting – and it is absolutely great to learn about the things to spot in winter that go on to become the fascinating beings of the summer months… Thank you Bob!

    25 Jan 2024 17:41:00

  • Gwyneth Waddington:

    I happened to spot a brown hairstreak in our garden last year and managed to get a couple of photos.

    25 Jan 2024 19:08:24

  • Heather Hedges:

    Loved the info, adds such interest to a winter walk. Off to see if I can spot a few now 🏃🏻‍♂️🏃🏻‍♂️🏃🏻‍♂️

    26 Jan 2024 12:19:00