Megachilidae > Megachile > Megachile pugnata
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. The female has a particularly large head with a spikey genal tooth on the cheek (like Halictus ligatus/poeyi), which sets her apart from other close relatives in the subgenus Sayapis.
Phenology
Summer, from June through August. Usually one generation per year, but known to be partially bivoltine in parts of its range.
Range
Widespread, most easily found in cultivated areas. Seemingly absent from coastal pine barrens, such as those on Cape Cod, Massachusetts.
Appearance
Size > honey bee
Females are large and elongate megachilids with bold bands on the abdomen. 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 have a banded abdomen and distinctive forelimbs that are modified into pale hairy “mitts”. In the field they are difficult to tell apart from males of closely-related M. inimica.
Similar species
- Female Megachile inimica sayi have smaller head and more slender cheek and no genal tooth. Both megachilids are commonly found on cultivated Asteraceae.
Nesting
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.
Foraging
Asteraceae, particularly composites like sunflowers (Helianthus), false ox-eye (Heliopsis helianthoides), coneflower (Echinacea), and cosmos (Cosmos).
Natural Enemies
Coelioxys alternata is a cleptoparasite. Checkered beetles Trichodes ornatus and chalcid wasps Melittobia spp. are also parasites.
References
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:
July 28, 2025