Macropis

Panzer, 1809

Loosestrife Bees

Species Guides

1

Macropis is a of solitary bees in the Melittidae, comprising approximately 16 described . These are the only known oil-collecting bees in the Holarctic region. They exhibit a highly specialized mutualism with plants of the genus Lysimachia (Primulaceae), whose flowers produce fatty oils that Macropis females collect using morphologically adapted hind legs. The genus is considered rare and has declined in many regions, likely due to loss affecting their specialized plant associations.

Macropis by (c) Julia Moning, some rights reserved (CC BY), uploaded by Julia Moning. Used under a CC-BY license.Macropis nuda f by The Packer Lab. Used under a Attribution license.Macropis nuda distribution by Wdsieling. Used under a CC BY-SA 4.0 license.

Pronunciation

How to pronounce Macropis: /mæˈkroʊpɪs/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Macropis are moderate-sized bees not exceeding 15 mm in body length. They are predominantly black in coloration; males possess conspicuous yellow markings on the . Females display distinctive morphological adaptations for oil collection: the tibiae are greatly enlarged and covered with dense velvety hairs that form the oil-collecting apparatus. A key diagnostic feature distinguishing Macropis from most other Melittidae is the presence of only two submarginal in the forewing (rather than three).

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Habitat

are restricted to areas where plants of the Lysimachia occur, particularly Lysimachia vulgaris in northwestern Europe and Lysimachia ciliata in North America. These include meadows, wetlands, and riparian zones where loosestrifes grow. Nests are excavated in ground soils.

Distribution

The occurs across the Holarctic region. In Europe, M. europaea and M. fulvipes are largely sympatric in southern Finland and the Baltic countries, while M. europaea alone extends through Scandinavia and most of Denmark. North American include M. nuda (widespread in Michigan and northeastern states), M. patellata (recorded from Michigan and Ontario), and M. steironematis. Records also exist from Alberta, Canada, and various eastern states including Connecticut, New York, Maine, and Nova Scotia.

Seasonality

Macropis are , producing one per year. Males emerge from ground nests in spring, typically a few days before females, and await females near plant flowers. In co-occurring species, temporal partitioning occurs: M. fulvipes exhibits some days earlier than M. europaea, potentially reducing . Activity is closely tied to the flowering period of local Lysimachia species.

Diet

feed on nectar. Females are oligolectic that collect both pollen and fatty oils secreted by flowers of Lysimachia (Primulaceae). In northwestern Europe, Lysimachia vulgaris serves as the main or sole pollen and oil source. Oils are used to provision larval and line nest cell walls.

Life Cycle

Development progresses from to larva to pupa within underground nests. Females construct nests with one or two terminal , provisioning each with a mixture of pollen and floral oils before laying a single egg. Larvae develop rapidly, pupating within approximately 10 days, then overwinter in the pupal stage. Nests are frequently parasitized by cleptoparasitic bees, particularly Epeoloides (including E. coecutiens in Europe and E. pilosulus in North America).

Behavior

Males exhibit mate-seeking by patrolling plant flowers and marking vegetation with from abdominal glands. Females demonstrate specialized oil-foraging behavior: rather than simply absorbing oil via capillary action, they actively break off oil-filled trichome from Lysimachia flowers using their modified hind legs. behaviors redistribute collected oils to the scopa and other body surfaces.

Ecological Role

Macropis bees function as specialized of Lysimachia , participating in a mutualism that likely originated in the distant past. Their oil-collecting involves structural co- with plant secretory systems. The serves as the exclusive host for rare cleptoparasitic bees of the genus Epeoloides, creating a three-level dependency chain: Epeoloides requires Macropis, which requires oil-producing Lysimachia.

Human Relevance

The has attracted conservation attention due to its rarity and specialized ecological requirements. declines have been documented, attributed to loss and reduction of Lysimachia plants. The Macropis-Epeoloides-Lysimachia system exemplifies the vulnerability of specialized mutualisms to environmental change.

Sources and further reading