Species in the genera Diadasia and Svastra are collectively called sunflower bees because, along with several other groups of plants, they are sunflower (Helianthus annuus) specialists. In addition to sunflowers, these bees specialize on mallows (Malvaceae), cacti (Cactaceae), evening primroses and willow herbs (Onagraceae), and wild bindweeds (Convolvulaceae). In fact, several cacti and mallows rely on sunflower bees for pollination services.

These bees are found in the New World and most occur in the United States and Central America, although several species do occur in Canada. Svastra spp. are moderate to large sized bees, usually between 7.5 and 20 mm long. They are hairy with pale hair bands on their abdomen. Males have long antennae.