Bidens alba, commonly known as Spanish Needle or beggar’s-tick, is a flowering plant in the daisy family native to Florida, the Caribbean, Mexico, and parts of Central and South America. This fast-growing herb or subshrub is easily identified by its small white-petaled flowers with yellow centers and its slender, dark seeds that readily cling to fur and clothing. Traditionally, it has been used in some cultures for medicinal purposes, such as for managing diabetes and hypertension, and it can also be a source of pollen for bees.

Despite its beneficial uses, Bidens alba poses a significant ecological threat. It is a highly opportunistic species that invades disturbed areas, agricultural land, and natural ecosystems, where it can form dense stands that crowd out native plants. Its high-risk invasive traits include prolific seed production, a long-lived seed bank, and effective seed dispersal by animals and humans. Once established, it can be difficult to control, making prevention and early detection critical, especially in tropical and subtropical island environments like Hawaiʻi.