Did you know that the Sonoran Desert is home to almost 1000 native bee species? Though most people are familiar with honey bees, these domesticated bees were actually introduced to North America from Europe — and honey bees are so widespread they in no danger of extinction. Native desert bees range from the world’s smallest bee (2 mm) to the large and clumsy carpenter bee (nearly 40 mm). Most are stingless, solitary nesters, aside from bumble bees. The majority of flowering plants in the Sonoran Desert are adapted to pollination by native bees.
You might find a native bee nesting in a tiny burrow in the ground, inside a hollow, pithy, dried stem, or in existing holes or tunnels in stumps and logs. This nesting habitat can often be threatened, unavailable, or contaminated with pesticides, which has contributed to a significant decline in native bee populations. Unlike social bees, a mother solitary bee prepares a large ball of pollen and nectar to sustain the larva once it hatches, seals the nest chamber, and has no further contact with her offspring.
Desert bees are busy in the spring searching for nesting material. Some bees line their tunnels with waterproof wax, while others collect floral oils and resins to help them build nests. You may have noticed circular shapes cut out of leaves and petals — this is a tell-tale sign of a leafcutter bee who requires those pieces to line her nest. Mason bees may take tiny pebbles, water, and mud to fashion adobe-like cells for their young.
Your garden will likely see many native desert bee visitors, on their quest for highly-nutritious pollen and sugar-rich nectar. The common cactus bee pollinates prickly pear, cholla, and saguaro cactuses (peek in a bloom and you might spot one coating itself in pollen). Carpenter bees can be found pollinating flowers on agave, tomatoes, melons, desert willow, and even crops such as cotton. Sonoran bumblebees visit snapdragons, sunflowers, and trumpets. Some specialized bees are more picky in their preferred food source, like tiny globe mallow bees, and digger bees that prefer creosote flowers.
A third of our crops rely on pollination from bee species. Crops such as squash, broccoli, cabbage, berries, cotton, and citrus are largely pollinated by native bees. Ground-dwelling bees also dig tunnels that are good for aerating soils and allowing water to percolate to roots. Bees provide food for ecosystems by generating fruit eaten by many animals, and by becoming food themselves. Our desert ecology and our agricultural economy benefit from healthy bee populations.
If you would like to read more about supporting native pollinators, check out this regional guide for farmers, land managers, and gardeners.