MERAUX, La. – Africanized honeybees, a fierce hybrid strain sometimes referred to as “killer bees,” appear to have established themselves in the New Orleans area, the state agriculture commissioner said.

A swarm of the bees was captured about five miles from where demolition workers found a colony of Africanized bees in January, commissioner Bob Odom said yesterday.

The most recent find was close enough to the earlier find that the bees might have come from the same colony. But they might also have flown ashore from a passing ship or barge, Mr. Odom said in a news release.

“Although the exact source can’t be identified, we have to assume Africanized honeybees are now established in the area and people should be careful when working outside,” Mr. Odom said.

The Department of Agriculture and Forestry keeps traps along a north-south line through the state and at all deepwater ports to monitor the bees, which are smaller and more aggressive than the European honeybees raised for honey.

“Because Africanized bees have been labeled ‘killer bees’ for years, there’s an idea around that they are bigger than European honeybees,” Mr. Odom said. “The truth is they’re actually smaller but a lot fiercer.”

They have the same venom as honeybees, but attack in groups. Experts recommend that anyone confronted with Africanized bees find cover quickly.

Africanized bees are the result of an experiment to increase honey production in Brazil. A swarm escaped a lab in 1957 and headed north. When they mated with native strains, the offspring were as aggressive as the African parents.

They reached Texas in 1990 and have spread west to California and east to Florida. They were first found in Louisiana in Caddo Parish, in June 2005, and identified the following month. They have moved steadily east since then, and were most recently found near Pecan Island and Turkey Creek.