Abstract. Tetragonisca angustula (Latreille) is a small, docile, cavity-nesting stingless bee that is widely distributed in the Neotropical region. This species is particularly abundant in disturbed environments, including human settlements. Between August 2005 and March 2006, we located and followed during eight months 59 nests of this species in Medellín, the second most populated city in Colombia. Herein, we document their foraging behavior, mortality, and incidence of predators and natural enemies. Also, to determine if higher ambient temperature and light intensity in urban environments affect the daily foraging activity of T. angustula, we compared the daily foraging activity of bees from nests found in open areas in the city and bees from nests from a nearby covered, forested area. Likewise, to determine if urban nests of T. angustula are largely undetected and undisturbed by people, we experimentally made them visible by adding a ring color (white, red, or black) around the nest entrance tube. Our observations indicate that higher ambient temperature and light intensity in urban environments do not significantly affect the daily foraging activity of T. angustula. Nearly half of the marked nests disappeared, thus suggesting that nests of T. angustula are often undetected by people in Medellín. We discuss briefly some features of the biology of T. angustula that might contribute to its success in urban environments.

A new species of the paracolletine genus Lonchopria Vachal, Lonchopria (Biglossa) comforti Gonzalez & Engel, new species, from high elevations in the Central Andes of Colombia is described and figured.  A preliminary key to the species of the Lonchopria subgenus Biglossa Friese is presented.  Recent records of bees occurring at elevations above 2500 m in Colombia and other Andean countries are also summarized.

We describe two new species of bees from Colombia; one is a species of Exomalopsis found nesting in the city of Medellin, Colombia, (the host) and its cleptoparasitic bee, a species of the genus Nomada. In addition, we provide information on the nest architecture of the new species and provide data on occupancy by both the host bee and its cleptoparasite. We present an updated list of the species of Exomalopsis and Nomada of Colombia and taxonomic keys to the species of Exomalopsis.