Cockroaches and Activation Theory

By Anupum Pant

Robert Zajonc, a Polish-born American social psychologist proposed an activation Theory for social facilitation. Sounds tough, but read on. His first theory, in simple words, tried to explain the way our performance at some tasks increases in the presence of others, while the performance at some other tasks decreases.

According to him, the presence of other individuals around you serves as a source of “arousal” and affects performance (in good ways some times and bad ways the other times).

When this happens, he said, humans tend to do well at tasks which they are inherently good at, or tasks which they’ve practised well, or easy tasks which involve very little conscious cognitive effort. While the performance at other complex tasks, which aren’t well-learned is affected negatively, when there are other people watching you.

More interestingly, he also pointed that this change in performance isn’t only seen among humans. ¬†An experiment that involved several cockroaches effectively proved this.

In two different cases, a cockroach was put in an easy maze to run around and find an exit. The first case had just the one cockroach running around in the maze. It did fine. But in the second case when there were other cockroaches watching the cockroach who was running in the maze, it ran faster. A clear increase in performance was noted in this easy maze.

Interestingly, when the difficulty of this maze was increased (it was a complex task now), as Robert had predicted, the cockroach’s performance decreased when other cockroaches were watching.

Wasp Uses Venom to Turn Cockroaches into Zombies

By Anupum Pant


The Emerald Cockroach Wasp A.K.A Jewel wasp – a metallic blue/green colored, 2 cm long wasp – is something that will blow your mind by the way it reproduces. More specifically, the Emerald Cockroach Wasp uses venom to hack into cockroach brains, turns them into zombies and lays eggs inside them. With time, this live yet immobile cockroach body is hollowed out by the larvae of the wasp and the young ones come out eventually.

How does it reproduce? (details)

At a time when the female Emerald Cockroach Wasp is ready to lay eggs, it competes with the other females to find a host to lay their eggs. When a wasp finds a good host – only this one kind of cockroach – the weird reproductive activity begins.

  1. The wasp attacks the cockroach and injects the first dose of venom into its central nervous system that is aimed at making the front legs of the cockroach paralyzed. Killing the cockroach with its venom is simple for the wasp, but keeping it alive is what matters here. So, the right amount of venom at the perfect place is injected.
  2. Now, when the cockroach can’t move its front legs, the wasp attacks again at a perfectly still moment to inject the second dose of venom. It carefully sticks the stingers into the brain of the victim in a way that the perfect amount of venom reaches the exact place in the brain of the cockroach which controls escape reflex. In short, it performs a micro neurosurgery and turns the cockroach into a zombie – Now it gets completely under control.
  3. Next, the wasp chews off half the antennae from the cockroach’s head and drinks its blood to gain energy.
  4. Then it grabs the cockroach by its antennae and hauls it into a burrow, lays the eggs on the abdomen of the cockroach, goes out and obstructs the entryway of the burrow using small pebbles to ensure that the host doesn’t escape. The calm zombie-cockroach is left in there to take care of the larvae for several days.
  5. The larvae hatches, drills a hole into the body of the cockroach, eats it from the inside, hollows is and comes out after a few weeks as a grown up wasp. The cockroach is dead.

Did you know? There is funny sticker selling on the internet – Jewel wasp vs. Zombie cockroach sticker. (Just FYI. I have no affiliation with it)