As of 2002, Africanized honey bees had spread from Brazil south to northern Argentina and north to South and Central America, Trinidad (West Indies), Mexico, Texas, Arizona, New Mexico, Florida and southern California. Their expansion stopped for a time at eastern Texas, possibly due to the large number of European-bee beekeepers in the area. However, discoveries of the bees in southern Louisiana indicate this species of bee has penetrated this barrier , or has come as a swarm aboard a ship. In June 2005, it was discovered that the bees had penetrated the border of Texas and had spread into southwest Arkansas. On September 11, 2007, Commissioner Bob Odom of the Department of Agriculture and Forestry said that Africanized honey bees established themselves in the New Orleans area. In February 2009, africanized honeybees were found in southern Utah
In tropical climates they compete effectively against European bees and, at their peak rate of expansion, they spread north at a rate of almost two kilometers (about one mile) a day. There were discussions about slowing the spread by placing large numbers of docile European-strain hives in strategic locations, particularly at the Isthmus of Panama, but various national and international agricultural departments were unable to prevent the bees' expansion. Current knowledge of the genetics of these bees suggests that such a strategy, had it been attempted, would not have been successful.
As the Africanized honey bee migrates further north, colonies are interbreeding with European honey bees. There are now relatively stable geographic zones in which either Africanized bees dominate, a mix of Africanized and European bees is present, or only non-Africanized bees are found (as in southern South America or northern North America).
Africanized honey bees abscond (abandon the hive and any food stores to start over in a new location) more readily than European honey bees. This is not necessarily a severe loss in tropical climates where plants bloom all year but in more temperate climates it can leave the colony with insufficient stores to survive the winter. Thus Africanized bees are expected to be a hazard mostly in the Southern States of the United States, reaching as far north as the Chesapeake Bay in the east. The cold-weather limits of the Africanized bee have driven some professional bee breeders from Southern California into the harsher wintering locales of the northern Sierra Nevada and southern Cascade range. This is a more difficult area in which to prepare bees for early pollination placement, such as is required for the production of almonds. The reduced available winter forage in northern California means that bees must be fed for early spring buildup.
Curiously, their arrival in Central America is a threat to the ancient art of keeping stingless bees in log gums even though they do not interbreed or directly compete with the stingless bees. The honey productivity of the africanized bees so far exceeds the productivity of the native stingless bees that economic pressures force beekeepers to switch. Africanized honey bees are considered an invasive species in many regions.http://en.wikipedia.org/wiki/Africanized_bee