Long-horned bees are solitary native bees in the genera Eucera and Melissodes, with numerous species found throughout Arizona's desert and grassland habitats. They are named for the males' remarkably long antennae — often as long as or longer than their body — which are used to locate females. Long-horned bees are ground nesters, excavating burrows in bare or sparsely vegetated soil, often in aggregations. They are oligolectic specialists on certain plant families, particularly Asteraceae (sunflowers, daisies, globe mallow) and are among the most important pollinators of native desert wildflowers in Arizona. Males are often seen sleeping communally on plant stems, clinging with their mandibles in characteristic 'sleeping clusters.' Long-horned bees are completely non-aggressive; males lack stingers and females rarely sting. They are active primarily in summer, coinciding with the bloom of their preferred host plants.