As their name suggests, solitary bees primarily live alone, unlike social bees that live in colonies. Although honeybees and bumblebees are social, about 90% of bee species are solitary, including various species of leafcutter (megachilid), carpenter, mason, and sweat (halictid) bees.  Some solitary bees are ground nesting and tunnel in sand, clay, and soil.  Others are cavity nesting and make nests in reeds and wood. Solitary bees are generally non-aggressive because they do not have hives to protect, like honeybees. Solitary bees do not have pollen baskets on their hind legs. As a result they spread more pollen while flying than social bees, and are excellent pollinators. By some estimates, solitary bees can be 50-200 times more efficient pollinators than honeybees! One is every three bites of food is pollinated by bees, making bees essential to our food supply.