Pugnacious leafcutter bee (Megachile pugnata) is a sunflower bee through and through. This distinctive, large megachilid is common in summer on composite asters in gardens, backyards, and agricultural fields. It has a particularly large head, including a genal tooth (like Halictus ligatus/poeyi), which sets it apart from close relatives of the subgenus Sayapis.
Summer, from June through August. Usually one generation per year, but known to be partially bivoltine in parts of its range.
Widespread, most easily found in cultivated areas. Seemingly absent from coastal pine barrens, such as those on Cape Cod, Massachusetts.
Size > honey bee
Females are large and elongate megachilids. Large heads with a prominent genal tooth, long vertex, and exaggerated space behind the compound eyes. Wings often held out at 45-degree angle while foraging.
Males are similar to other Sayapis megachilids and difficult to identify to species in the field.
- Female Megachile inimica sayi have smaller head and more slender cheek and no genal tooth. Both megachilids are commonly found on cultivated Asteraceae.
Above-ground cavities. Known to nest in trap nests. Common in cultivated habitats where like backyards, vegetable gardens, and agricultural fields. Absent from sandy coastal areas.
Asteraceae, particularly composites like sunflowers (Helianthus), false ox-eye (Heliopsis helianthoides), coneflower (Echinacea), and cosmos (Cosmos).
Coelioxys alternata is a cleptoparasite. Checkered beetles Trichodes ornatus and chalcid wasps Melittobia spp. are also parasites.
Tepedino, V. J., & Frohlich, D. R. 1982. Mortality factors, pollen utilization, and sex ratio in Megachile pugnata Say (Hymenoptera: Megachilidae), a candidate for commercial sunflower pollination. J. New York Entomol. Soc., 90: 269-274.
Page last updated:
January 17, 2023