The Elusive Demiguise

"Lorcan heard his brother's quiet signal, a robin's song, and counted down. 3… 2… 1… NOW! He thought, leaping out from behind a shrub of his own. The boys landed on the figure and tried to wrestle it to the ground, but well-muscled arms pulled them off and deposited them on the ground." What happens when Lorcan and Lysander try to catch a Demiguise? For lilac butterflies' SRC.