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Macropis cuckoo bee 

Scientific Name

(Epeoloides pilosula)

The Macropis cuckoo bee was initially thought to be extinct until it was rediscovered around the turn of the century (1, 2, 3). Since then, it has been reported a few times across the continent (1, 2, 3, 4). This species is likely endangered due to the nest loss of its uncommon host genus of bees (Macropis), which in turn depend on a specific genus of flowers (Lysimachia) for food (1, 2). The species historically ranged through most of eastern North America, from Massachusetts to Georgia and west towards Montana extending into Canada (1, 2, 3, 4). It has not been seen in Maryland for over a century (1, 2, 5).

Identification 

Macropis cuckoo bees have a shiny black-brown body about 7.5–10 mm in length. They differ from other cleptoparasitic bees in having dorsal bands of erect, feathery white hairs (1, 2). They appear humpbacked, with the thorax raised above the level of the head. The hair on the hind legs of females is as sparse as on other legs, while the males have unusually enlarged middle and hind legs (5). The males also have large eyes with a distance between them that narrows towards the top of their head (1, 2, 5).

Life cycle

Macropis cuckoo bees are parasites that attack the nests of their namesake, the oil-collecting Macropis bees, which are uncommon oligoleges, or specialists, for Lysimachia flowers (1, 6). The adults of the parasitic bees take flight in June and July, corresponding with peak activity from the host bees and flowers. They feed on pollen and nectar from several plants, but Lysimachia remains important as that is the host's specialty (1, 2). After mating, the females seek host nests to lay eggs in, which hatch into larvae that consume food intended for the host. The larvae then wait out the winter before continuing development (1). The name "cuckoo" is synonymous with an organism that relies on another to raise its offspring (6), similar to the cuckoo bird, which parasitizes other birds' nests.

Two Macropis species have been reported in Maryland, including M. ciliata, and M. patellata. Click here for further information on the genus.

Habitat

Lysimachia typically grows in moist areas such as swamps and ditches, while Macropis bees build nests nearby in sandy soil exposed to the sun. However, the distance between host flowers and bees can often be far enough to prevent contact, leading to the decline of nests and bees (1, 2). 

Lymanchia ciliata (Fringed Loostrife)  is shown right.