Africanized honeybees (AHB) are actually a subspecies of the European honeybee, and the two look exactly the same. Only an expert making numerous microscopic measurements can tell the two apart. The difference, however, becomes readily apparent in the aggressiveness of the AHB when its colony is disturbed, lending to its nickname “killer bees.” The AHB releases an alarm pheromone that calls all the workers to “battle” where they will attack and sting any moving animal or object. They will chase and sting people for hundreds of yards and have been known to sting people and pets over a whole neighborhood block. Deaths may occur due to allergic reactions from the larger number of stings received. It may take hours for the bees to settle down and return to the colony. Other honeybees will attack and sting for a few minutes and then settle down rather quickly.
Africanized hybrid is initially feared because it tends to retain certain behavioral traits from its African ancestors that make it less desirable for domestic beekeeping. They are about 1/2-inch in length and golden-yellow with darker bands of brown. Some specimens appear a darker brown than others.
In the United States, the AHB has become established from Texas over to southern California. Colonies have also been discovered in Florida and a few other southeastern states but these have been quickly eradicated. In the wild, honeybees most often nest inside cavities of trees, but they will also nest within caves and cracks in rock formations. Occasionally, a colony will decide to nest inside a crawl space, an attic, a wall void, or a chimney in a home.