This diminutive butterfly seems equally at home on chalky or slightly acidic soils, preferring in both cases free-draining dry grassland areas. At first glance it can be confused with a female common blue due to a number of similar features. Caterpillars of the brown argus are tended to by ants. They care for the caterpillar and drink a fluid secreted from the insects’ honey gland - an example of symbiosis in action.