After a single reward on a spectral color, freely flying honeybees show retrograde amnesia when an electroconvulsive shock, CO2 narcosis, N2 narcosis, or cooling (to 1 degrees C) is applied after learning. Retrograde amnesia is measurable with these four treatments up to 7 min after the reward. For none of the treatments was a consistent relationship found between the reaction tested and the time of testing after the treatment. Prolonged application of the four treatments leads to a significant increase in the rate of retrograde amnesia only after CO2 narcosis. Memory in the honeybee is susceptible to impairment until 15 min after the reward.