Robert L. Jeanne, an entomologist at the University of Wisconson, zoomed his camera in on the entrance to a nest of Polybia occidentalis wasps in Guanacaste, Costa Rica. About 5 seconds into the movie, the tip of a soda straw appears just above the bottom margin of the screen.
A light exhalation through the straw onto the resting wasp just above it raised the alarm. The following several seconds show the spread of alarm to other wasps nearby and inside the nest.
Jeanne suspects alarm spreads as nearby wasps detect wasp venom. The venom acts as a chemical signal, or pheromone, Jeanne believes. Circumstantial evidence indicates that alarmed wasps amplify the signal by themselves releasing a bit of venom and fanning their wings to disperse the pheromone.
In the video, watch for the plastic straw to enter the frame from below.
© Robert L. Jeanne