Bee of the Month – Hylaeus mesillae
Also known as "masked bees," these tiny, hairless, black bees usually have distinctive yellow markings on their faces. The females have a pair of yellow vertical marks on either side of the lower middle face just inside the compound eyes, while males have a broader central yellow mark in addition to their lateral facial stripes. Females lack the an external pollen transport structure, and use the digestive tract to transport pollen internally.
They resemble some Lasioglossum, Ceratina, and Andrena bees. Hylaeus encompasses 150 species worldwide, and within North America there are 50 species. Of those 50, 26 are within California and we have found 11 at our garden sites, mostly H. mesillae, H. polifolii, H. punctatus, and H. rudbeckiae.
Hylaeus can be found slowly and deliberately flying around from March into October, commonly found on Achillea, Aster, Ceanothus, Eriogonum, Phacelia, Salvia, and Solidago. They are solitary bees and will nest in tunnels such as beetle burrows and hollow stems.
Look out for these tiny bees in your garden!