Carlos Solis
A team at the University of Sydney watched a common house cricket (Acheta domesticus) carefully groom an antenna that a heated pin had poked — not just twitch away in a reflex.
Measuring pain is hard: even in people the most direct test is asking someone to rate it on a zero-to-10 scale. Subjective pain matters because it implies the capacity for feelings and emotions, not just automatic bodily reactions. Because you can’t ask a cricket, researchers look for behaviors that could indicate a subjective pain experience.
In 2022, animal-behavior experts proposed eight criteria to help judge whether an animal might have that kind of experience. The list started with crustaceans (crabs, lobsters, and the like), but researchers now use it more broadly. Meeting any of the items suggests an animal’s reactions may go beyond simple reflexes.
- Nociception — receptors that detect harmful stimuli.
- Sensory integration — brain regions that combine information from multiple sources.
- Integrated nociception — neural pathways linking damage-detecting receptors to integrative brain areas.
- Analgesia — painkillers change the animal’s response to a harmful stimulus.
- Motivational trade-off — the ability to weigh possible harm against reward, showing flexible decision-making.
- Flexible self-protection — after injury the animal grooms or guards the wound, licks it, or rubs the damaged area.
- Associative learning — linking harmful stimuli with neutral cues or learning ways to avoid them.
- Preference for analgesics — for example, choosing pain relief even over food when injured.
Some insects already meet several of these criteria: flies and cockroaches meet six items, while other insects meet four. Crickets are one of the most widely farmed insects in the world, raised for human food, animal feed, and research, and today more than 370 billion crickets are farmed each year.
To test for self-protective behavior, the University of Sydney team led by entomologist Thomas White and philosopher-biologist Kate Lynch lightly touched crickets’ antennae or poked them with a pin heated to 65 °C (149 °F).
Both males and females did more than reflexively pull away. The crickets groomed and licked the antenna that had been touched with the heated pin twice as often as when researchers used an unheated pin or when there was no contact. The temperature was high enough to activate “pain receptors” but too low to cause lasting damage.
After each stimulus, the scientists watched the insects for ten minutes. White and Lynch wrote in The Conversation: “They treated the heated side, not both antennae. And this wasn’t a short reflex: activity rose at the start and then gradually declined over minutes, similar to how we rub a burned hand until the sting fades.”
Earlier studies already showed crickets have nociceptors, centralized sensory integration, associative learning, and that analgesics can change their responses. Adding flexible self-protection means crickets meet at least five of the eight criteria.
Taken together, nociception, integrative processing, learning, and goal-directed self-protection make a strong case for considering cricket sentience.
The results were published in Proceedings of the Royal Society.
Photo: Unsplash
