Thermal investigations were performed in Colombia on a colony of the stingless bee Tetragonisca angustula by means of thermometry and direct calorimetry. To this end, a nest with approximate 5000 individuals was collected in the field and transferred to a twin calorimeter, where the bees continued their normal life and development. Two camping boxes (Poor Man's Calorimeter, PMC) with Peltier elements as cooling systems were used as a differential system. Each box had a volume of 8 L and a sensitivity of 19.2 mV W-1. The PMCs were modified to give forager bees a free access to the environment. The thermal situation within the colony was monitored calorimetrically and thermometrically. 10 k Omega of NTC resistors were distributed at special points of the brood combs, storage pots and involucrum. The thermometric and calorimetrical signals were recorded continuously over 3 months by a four-channel data logger. (C) 2007 Elsevier B.V. All rights reserved.