A study has revealed a new defense mechanism used by bees when attacked by giant “murder” hornets: screaming. When left unchecked, the giant Asian hornets can destroy a honeybee hive in hours, feeding on larvae and decapitating bees in what scientists call a “slaughter phase”. The hornets then feed severed body parts to their young. The study, published in the Royal Society Open Science journal this week, revealed that bees release a “rallying call for collective defence” against the hornets. The previously undiscovered signal, now known as an “anti-predator pipe, shares acoustic traits with alarm shrieks, fear screams and panic calls of primates, birds and meerkats,” according to the study. Bees produce the sound by vibrating their wings or thorax, elevating their abdomens and exposing a gland to release a pheromone. “It’s alarming to hear,” Heather Mattila, a co-author of the study, told Gizmodo. “It’s characterized by rapid bursts of high-pitched sounds that change unpredictably in frequency – they’re quite harsh and noisy.” According to the study, signal rates increase seven- to eight-fold during a hornet attack. In addition to anti-predator pipes, bees resort to “fecal spotting” – a defense mechanism in which they collect animal feces and apply it to the entrance of their hives to deter the hornets. Other measures include “balling”, where bees will form into a cluster and smother the hornet by vibrating their wing muscles. The vibration-fueled heat, which can reach up to 46C, coupled with the carbon dioxide produced by the bees, can kill a hornet in 30 minutes. In recent months, giant hornets have increasingly emerged in the Pacific north-west region of the US. In September, the third giant hornet nest to be discovered in the country this year was found in Washington state. The hornets are an invasive species with nests that are very difficult to locate, as they tend to be in forested areas. In addition to causing devastating harm to bee colonies, the giant hornet can harm humans, at times causing fatalities. One entomologist has described the feeling of being stung by a murder hornet as like “having hot tacks pushed into my flesh”. The hornets can also eject venom.