After interbreeding, Africanized strains migrated north, reaching Texas in 1990.

FORBES: Magazine Article

Africanized honey bees, known colloquially as "killer bees, " are believed to have entered Texas in 1990 and have since spread to at least 10 other states, from California to Florida.

CNN: Africanized bee swarm kills Texas man

Allen Miller, whose company Bees Be Gone removed the hive after the attack, said he's seen more Africanized bee hives in the past few weeks than he normally sees in a year.

CNN: Africanized bee swarm kills Texas man

Africanized honey bees, which are hybrids of African and European bees, can be highly defensive around their nests and swarm more frequently than other honey bees, according to the U.S. Department of Agriculture.

CNN: Africanized bee swarm kills Texas man