Moving towards Spring means possibly issuing our infamous ‘Swarm of Bees’ advisories. We issue the bee advisories because some people are deathly allergic. Nancy Troyano, an entomologist with Western Exterminator, explains why the bees are so dangerous. “They are very aggressive and they will sting in great numbers,” Troyano said. “And they will pursue a threat for up to a quarter of a mile."