Painted dark bee (Stelis louisae)

Megachilidae > Stelis > Stelis louisae

Louisiana painted-dark bee (S. louisae) is a colorful and distinctive member of an otherwise rare and poorly understood group of megachilid cuckoos. S. louisae is thought to predominately parasitize nests of megachilids that line their nests with tree resin: Megachile campanulae in New England and M. exilis in mid-Atlantic states. S. louisae typically forages on summer-blooming Asteraceae in human-disturbed habitats like gardens and agricultural fields, and they hold their smoky-dark wings out while foraging.


June to September. One generation per year.


Maryland to Massachusetts and southern New York. Range overlaps with Megachile exilis in the mid-Atlantic and Megachile campanulae in the northeast.


Size < honey bee

Females strongly marked face with yellow vertical lines on the inner margin of the compound eyes; thorax rimmed in thin yellow border; abdomen T1 thick yellow band (with orange highlights), T2 widely broken, thin yellow band, and smaller yellow markings on T3-T5; brownish legs; dark purple wings held out during foraging; scopae absent.

Males like females.

Similar species

Resembles no other Stelis in the northeast.

Superficially, Paranthidium jugatorium is similar, but has evenly thin, broken bands on all abdominal segments, and females have abdominal scopae.


Cleptoparasite of Megachile in the subgenus Chelostomoides. In New England, host is M. campanulae. In Mid-Atlantic (northern New Jersey and south), host is M. exilis.


Asteraceae, sunflowers (Helianthus), false ox-eye (Heliopsis), goldenrod (Solidago). Also recorded from mountain mint (Pycnanthemum), vervain (Verbena), and butterflyweed (Asclepias tuberosa).

Natural Enemies

No enemies reported.

Page last updated:
January 17, 2023