### q2 serotonin production is triggered by touch > The specific signal that instigates the phase shift varies from species to species, Song said. For example, although both species react to the sight and smell of other locusts in a laboratory setting, the desert locust can shift into the gregarious phase with a touch on the hind legs, whereas the sensitive area on the Australian plague locust (*Chortoicetes terminifera*) is its antennae, he explained. These triggers seem to boost levels of serotonin, the same chemical associated with mood in humans. - [View Highlight](https://read.readwise.io/read/01fn7bbx00k1ynxr5ag53cvmy4) - [[What Are Locusts and Why Do They Swarm by Greg Uyeno#q2 serotonin production is triggered by touch|View in Vault]]