Osmia pumila

Cresson, 1864

Osmia pumila is a solitary to eastern North America. It is strongly associated with forest , where it performs spring of wildflowers and possibly some timber trees. The nests in pre-existing cavities such as hollow stems or holes in wood, sealing chambers with mud. Research indicates it is one of the most common forest-associated species in the eastern United States, with increasing as forest cover has regrown since the early 1900s.

Osmia pumila, M, Face, MD 2013-06-25.18.39.16 ZS PMax (9302552275) by Sam Droege from Beltsville, USA. Used under a Public domain license.

Mason Bee - Osmia species, possibly pumila, Leesylvania State Park, Woodbridge, Virginia by Judy Gallagher. Used under a CC BY 2.0 license.

Osmia pumila, M, Back, MD 2013-06-25.18.25.15 ZS PMax by Sam Droege. Used under a CC BY 2.0 license.

Pronunciation

How to pronounce Osmia pumila: //ˈɒs.mi.ə ˈpjuː.mɪ.lə//

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Identification

Osmia pumila is one of more than three dozen identified as clearly forest-associated in a comprehensive study of eastern North bees. It can be distinguished from similar Osmia species by its strong association with forest rather than agricultural or urban environments. Males and females have been photographed and documented by the USGS Bee Inventory and Lab. Specific diagnostic morphological features are not described in available sources.

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Habitat

Primary is temperate deciduous forest. A five-year field study in New Jersey, New York, and Pennsylvania identified O. pumila as one of the most common clearly forest-associated , rarely found outside forest habitat. The study found that both diversity and sizes of forest bees, including O. pumila, were greater in larger forest . Historical museum records from 1872-2011 confirm its persistence in eastern forests through periods of logging and subsequent reforestation.

Distribution

to eastern North America. GBIF records indicate presence in Middle America (Central America) and North America. The was documented in a study spanning New Jersey, New York, and Pennsylvania. Historical specimens range from West Virginia and Ohio to Maine.

Seasonality

Spring-flying . Emerges and is active during April and May, coinciding with spring wildflower bloom in temperate forests.

Diet

Pollen and nectar forager. Specific sources are not documented in available sources, though it likely contributes to of spring-blooming forest wildflowers and possibly maple trees.

Life Cycle

Solitary with cavity-nesting . Females construct in pre-existing tubular spaces, provision them with pollen cakes, , and seal chambers with mud. develop within sealed chambers, consuming pollen provisions through summer and autumn, overwinter as mature individuals, and emerge the following spring. Males exhibit protandry, emerging several days before females.

Behavior

Females spend time in the nest between pollen and nectar foraging bouts, adjusting time in nest based on food availability and presence of . When food resources are scarce and parasites are present, spend less time in nest and make more frequent food foraging trips. Males guard mates after mating to prevent interlopers.

Ecological Role

Important spring in forest . Pollinates spring-blooming wildflowers and possibly some timber trees such as maples. Serves as for cleptoparasitic Sapyga centrata, which enters nests to oviposit while female are away foraging.

Similar Taxa

Osmia lignariaBoth are North that nest in cavities and are active in spring. O. lignaria is the orchard , widely used commercially for orchard and found in more open , while O. pumila is specifically forest-associated and not commercially managed.
Osmia cornifronsBoth are spring-active . O. cornifrons is to Asia and was intentionally to North America in 1978 for orchard . It has stable and is commercially shipped, whereas O. pumila is native, forest-dependent, and not involved in commercial trade.
Osmia taurusBoth are spring-active found in eastern North America. O. taurus is a non- from eastern Asia, first discovered in the U.S. in 2002, with rapidly expanding . It is difficult to distinguish from O. cornifrons in the field and has been associated with declines in native Osmia species, whereas O. pumila is native and forest-associated.