Fig. 2.

Mandibles from 11 stingless bee species and the honey bee (Apis mellifera) for comparison, showing the presence of teeth, particularly on Trigona. The pain caused by biting is shown on a scale of 0–5 where 0 = could not be induced to bite, 1 = biting was visible but could not pinch skin, 2 = able to pinch skin but caused no pain, 3 = very mild pain, 4 = moderate pain, and 5 = sharper unpleasant pain and capable of breaking skin if persistent. All pictures to same scale