The Africanized hybrids spread throughout South America and Central America, moving at a rate of 250 to 350 miles per year. In the fall of 1995, the bees entered southeastern California. Africanized honey bees are physically similar to European honey bees. There are few distinctive traits that can be observed with the naked eye. Definite identification must be performed in a laboratory where more than 20 different structures are measured and compared, or the DNA and enzymes are analyzed.
More apparent differences lie in the behavior of the bees.
Africanized honey bees are highly defensive and easily agitated. In as little as three seconds, they will respond to a perceived threat with considerable force. European honey bees take as long as 30 seconds to react to a perceived threat. Africanized honey bee colonies have a larger proportion of soldiers among their workers than European colonies. During an attack, the Africanized honey bees deliver as many as ten times the number of stings as their European counterparts.