A particularly aggressive strain of honey bee has been menacing parts of Arizona in recent weeks, with some people getting stung so many times that they've been hospitalized.

In the past week alone, an 84-year-old man from the Tucson area was stung more than 2,000 times in his backyard. Three dogs have been killed. And beekeepers report an increase in calls to remove hives and bee swarms.

Some answers to common questions about the bee attacks:

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WHAT KIND OF BEES ARE ATTACKING?

Experts point to the Africanized honey bee, also known as the killer bee, which is a cross-breed between the European honey bee and the African honey bee, according to Reed Booth, who runs a bee-removal business in Bisbee, in southern Arizona.

The killer bee is the result of experiments in Brazil decades ago, and the insects migrated to the U.S. The bees are more prevalent in warm Southwestern states such as Arizona, New Mexico, and Texas. If their hives are disrupted, they become especially aggressive.

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WHAT IS A NORMAL BEE SEASON?

In a normal year, bee season runs from mid-March through late October, but it often depends on the weather.

"I normally get five to 10 calls a day for bee removal, and now you're getting 30 to 60 every day," Booth said.

The Phoenix Fire Department has responded to 58 bee calls in the metropolitan area since the start of 2014, including 17 this year, Capt. Aaron Ernsberger said.

Elaine Stacey, who co-owns a bee-removal service in Phoenix, has also noticed an increase in Africanized honey bees in Arizona, especially in the spring.

Booth could not pinpoint an exact reason for the increase, but he believes the change is due to the wet, warm winter Arizona experienced this year.

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WHAT CAUSES THEM TO ATTACK?

The bees are constantly on guard for possible threats to the hive. They could perceive the color of a shirt or the scent of cologne as threatening, Booth said. It doesn't take much to provoke them.

"They hate any movement, noise, or vibration," Booth said. "They hate everything."

Booth said he has also witnessed a behavioral shift in the Africanized honey bee, with their aggressiveness going "through the roof."

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HOW FEROCIOUS ARE THE BEES?

An 84-year-old Oro Valley man survived after being stung by more than 2,000 bees in his backyard. Booth said 500 stings are the equivalent of one rattlesnake bite.

In Arizona, signs along popular hiking trails warn about the dangers of bee hives. Spring training baseball games are sometimes disrupted by swarms of bees, and pets sometimes fall victim to the attacks.

A woman driving through the Phoenix suburb of Peoria this week was swarmed by bees that were disturbed by a landscaping crew. Her dog was killed. A swarm also attacked a person in the Prescott area and killed two other dogs this week.

The sizes of the hives and swarms vary, but Booth said an average hive usually has 40,000 to 60,000 bees.

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WHAT CAN PEOPLE DO?

Phoenix fire officials recommend that anyone who encounters bees leave the area, call 911 and notify a beekeeper.

Additionally, people who are allergic to bees should be sure to carry medicine with them, Ersnberger said.

"If you see a bee, just don't go near it," Booth said.

Health officials also advise people who disrupt a beehive to cover their heads, run away and take shelter and not to flail their arms.