Paper wasps are known for their aggressive behavior and their ability to deliver painful stings. However, a new study has shown that these wasps also have a surprisingly strong memory for previous encounters.

The study, published in the journal "Animal Behaviour," found that paper wasps were able to remember individual humans for up to three days. This is a remarkable feat of memory, considering that paper wasps have a brain that is only about the size of a pinhead.

The study was conducted by researchers at the University of California, Riverside. The researchers placed paper wasps in a small arena and then introduced a human hand into the arena. The wasps would typically respond to the hand by stinging it.

The researchers then removed the hand and replaced it with a different human hand. The wasps were much less likely to sting the second hand if it belonged to the same person who had presented the first hand. This suggests that the wasps were able to remember the first person and associate them with a negative experience.

The researchers also found that the wasps were able to remember the human hand even if it was presented in a different context. For example, the wasps were still less likely to sting the second hand if it was presented in a different room or if it was attached to a different body.

This suggests that the wasps were not simply responding to the visual appearance of the hand, but that they were actually able to remember the individual person who had presented the hand.

The researchers believe that this strong memory for previous encounters may help paper wasps to avoid predators and to compete for resources. By remembering individual humans, paper wasps can avoid people who have previously harmed them and they can also target their aggression towards specific individuals who are competing for the same resources.

This study provides new insights into the cognitive abilities of paper wasps and it suggests that these wasps may be more intelligent than previously thought.