SummaryUsing a laboratory test, newly emerged worker honeybees(Apis mellifera)were evaluated for their response to four alarm pheromones (isobutyl acetate, isopentyl acetate, 2 heptanone, 1 pentanol), under five temperature/humidity regimens (30°C, 30 6°C, 26°7°C, at 45% RH; 35°C at 30% and 85% RH). With a higher temperature, there was increased probability of a response, and the speed, intensity and duration of that response were also greater. Relative humidity seemed to affect only the intensity, higher humidities increasing it. Occurrence of Nasonov fanning as a part of the response by some bees depended largely on the pheromone being tested; the effects of temperature and humidity were less clear-cut.