it typically feeds on flowers of plants in the mustard family for food. In Southern Germany, it collects its pollen from the wild mustard plant (Sinapsis arvensis). This plant does not grow on vertical surfaces, but instead on fields. Therefore, the only way A. agilissima can forage on this plant is when it close to an area that it can use as a nesting site. Due to the changing agricultural landscape of many places, there have been fewer A. agilissima. It is now rare to find large nest aggregations, which also impacts its cuckoo bee Nomada metalthoracica. The cuckoo bee lays its eggs in the host nest. In south-west Germany, it has been attempted to change the way fields are ploughed and planted so that the bees can feed on these wild mustard plants. This has caused for A. agilissima to start to form meta populations, or a collection of smaller local populations that have local extinctions, colonizations, and sometimes dispersal between the populations. A. agilissima - like Osmia brevicornis - also feeds on Brassicaceae (mustard plants). There is a huge aggregation of this bee in Tuscany, Italy on an earth wall 2.5 m high and 6 m wide. Behavior Mating The males search for virgin females while the females are collecting pollen from flowers. Bees in the genus Andrena are receptive to mating soon after leaving the nest as a mature bee, but are not receptive to male attention some time afterwards. Females mate only once. This bee is a communal bee where they are about 5-50 females sharing a nest entrance. It is found that most of the females have already mated before they permanently leave the nest. This is different from other bees in the genus which are usually solitary bees. Mating in the nest typically happens at the beginning of spring and mating at flowers happens at the end of the flight season. Being farther from the nest and mating will help lower the chance of inbreeding. Size dimorphism The males do not show discrete size dimorphism unlike other bees and all are able to fly. The females are bigger than the males with a slightly larger head size. There is no correlation of how big the female bee is compared to the amount of pollen that is being transferred. The carrying capacity is about 6.3 to 37.5% of its own body weight. Foraging At the