Wasps and bees often fly into soft drink cans unnoticed resulting in painful stings of the lips, tongue and mouth. Bees are attracted to flowering plants and therefore, careful selection and placement of plants for yards is important for those who are allergic to these insects. Certain colors also appear to attract bees and wasps. Blue clothing in particular seems to be associated with more unprovoked stings. Threatening a hive by approaching too closely or by making loud noises or vibrations often results in multiple stings.
Africanized bees are much more aggressive in defending their hives than are European bees.
When an Africanized bee stings, it marks it's victim with a chemical marker that attracts other bees from the hive. Thus, if one threatens a hive of Africanized bees one can expect to be pursued by thousands of bees. These bees have been known to pursue people for long distances. It does not take much to make an Africanized bee feel threatened. Approaching too close to the hive or operating machinery that transmits vibration to the hive will provoke an attack.