Brown Argus Aricia agestis


The Brown Argus was traditionally associated with calcareous grasslands, and the loss of this habitat to agricultural improvement in southern and central England led to the butterfly's rapid decline until the 1990s when it began a dramatic expansion of its range, particularly in the north and east. It has colonised roadside verges, disused railway lines and rough land created by set-aside. It is also found in coastal dunes and heathland.


The Brown Argus is brown with prominent orange spots on the upper wings which extend to the wing tips on females. It can be confused with a number of other butterflies: it resembles the female Common Blue, but is noticeably smaller and lacks all traces of blue near the base of the wings. The undersides differ in that the Brown Argus has almost vertical twin spots on the top edge of the hindwing, and has no cell spot on the forewing. It can also be confused with female Chalkhill Blue and Adonis Blue, but they are both much larger. It has a characteristic silvery appearance in flight.

Flight times

Throughout most of its range it is double brooded, flying from early May to the end of June and mid-July to mid-September, but in Derbyshire it is usually single brooded and on the wing during June and July.

Food plants

Eggs are laid singly on the under-surface leaves of Common Rock-rose on calcareous soils, elsewhere it favours Common Stork's-bill and various crane's-bills.

Distribution Maps

Brown Argus distribution map 2005-09
Brown Argus distribution map 2010-14
Brown Argus distribution map 2015-19
Brown Argus distribution 2015
2015 Summary
No of tetrads 109
First sighting 04/05/2015
Last sighting 29/09/2015
Brown Argus distribution map 2016
2016 Summary
No of tetrads 88
First sighting 08/05/2016
Last sighting 16/09/2016
Brown Argus distribution map 2017
2017 Summary
No of tetrads 102
First sighting 04/05/2017
Last sighting 13/09/2017
Brown Argus distribution map 2018
2018 Summary
No of tetrads 169
First sighting 13/05/2018
Last sighting 25/09/2018
Brown Argus distribution map 2019
2019 Summary
No of tetrads 159
First sighting 23/04/2019
Last sighting 22/09/2019
Brown Argus distribution map 2020
2020 Summary
No of tetrads 116
First sighting 06/05/2020
Last sighting 05/10/2020
Brown Argus distribution map 2021
2021 Summary
No of tetrads 128
First sighting 16/05/2021
Last sighting 26/09/2021
Brown Argus distribution map 2022
2022 Summary
No of tetrads 126
First sighting 29/04/2022
Last sighting 21/09/2022

Photo Gallery