Access: From Arette, follow the D132 towards La Pierre-Saint-Martin. After about 6.5 km, park on the left on a grassy area at a place called La Mouline.
(S/E) From the car park, cross the Vert d'Arette ford and join the main track that branches off to the left. Very quickly, it climbs in wide hairpin bends through the Bois de l'Oumbré-det-Hourcq, which provides some shade if needed.
(1) Every other bend offers beautiful views of the valley and the opposite slope. Continue climbing in more open terrain or along the edge of the woods
(2) You will reach the Cabane d'Auriste, located in a vast meadow where cows graze and goats prefer the steeper corners. This spot, with its distant views, is ideal for a well-deserved break.
Continue along the path, which veers slightly to the right. Just before reaching the highest point, look out for a pile of puddingstone boulders on the left.
(3) From the summit of Mail de Lerre, the view stretches towards the Pics d'Arlas and Anie beyond the Pierre Saint-Martin.
(4) When the trail begins to descend, turn around and return by the same route but downhill (S/E).