The antenna of House cricket (Acheta domesticus) exhibits fascinating behavior when contacted with a heated probe. Insects show heightened attention to the burned area, grooming it much more significantly than if there were either innocuous contact or no contact at all. This phenomenon, observed by entomologists from the University of Sydney, may provide evidence for a condition akin to pain in insects, a topic that has sparked considerable scientific debate.
Manzi et al. explored house crickets (Acheta domesticus), a key species in insect farming, emphasizing the importance of flexible, site-specific self-defense as a pain-related behavioral feature. Image credit: Matthew Lindsey / CC BY 2.0.
“Once thought to possess brains too simple for complex experiences, insects are now recognized for their ability to perform intricate tasks like associative learning and situational decision-making,” said Dr. Thomas White, an evolutionary ecologist at the University of Sydney.
“Recent studies have pinpointed brain regions such as the mushroom body and central complex that seem to facilitate evaluative processing similar to mechanisms found in vertebrates.”
“However, understanding pain in insects cannot be resolved solely by examining neural structures.”
“Considering the variety of nervous systems across different species, behavioral observation remains the clearest path to inferring subjective experiences.”
“Thus, rather than questioning whether insects share the same neural structures, it is more pertinent to investigate whether they display similar behaviors under comparable conditions.”
In their research, the authors assessed 80 adult house crickets under strictly controlled experimental conditions designed to dismiss simple reflex actions.
Each cricket underwent exposure to three specific conditions: the tip of a soldering iron heated to 65 degrees Celsius (149 degrees Fahrenheit) was briefly applied to one antenna, followed by a non-heated probe application, alongside a no-contact scenario.
Cameras recorded the crickets’ movements for ten minutes, while three observers, blinded to the treatment each insect underwent, analyzed the grooming behavior frame by frame.
Results showed that crickets exposed to heat stimulation were significantly more prone to groom the affected antennae, dedicating considerably more time to this behavior—about four times longer than their counterparts in the no-contact group.
On average, the duration of grooming for damaged antennae reached approximately 13 seconds post-exposure, contrasted with around 3 seconds in the control condition.
“The increased grooming intensity in crickets followed a clear temporal pattern; those subjected to noxious heat displayed a heightened and sustained response, which later declined. This behavior mirrors findings in bees and rodents,” the researchers noted.
What makes this discovery particularly significant is not merely that the crickets responded, but how they did so.
Reflexes—often automatic responses that even the simplest nervous systems exhibit—typically cease once the stimulus is removed.
In contrast, the crickets continued returning to the impacted area long after the heated probe was taken away, indicating they were likely tracking an internal signal of damage.
“Pain represents one of the most enigmatic and crucial aspects of animal cognition, positioning insects as a challenging case study,” the authors remarked.
“Behavioral indicators, particularly flexible and localized responses to harm, offer the most straightforward method to deduce pain-like states in these creatures.”
“Our findings showcase such a response in a crucial organism: Acheta domesticus. Crickets exhibited more frequent grooming, prolonged duration, and a distinct temporal profile in response to noxious stimulation compared to tactile or non-contact controls.”
“These responses were specific to the injury site and persistent, indicating that crickets monitor the vicinity of the harm and adjust their behavior beyond mere reflex actions.”
Findings are detailed in a study published this month in Proceedings of the Royal Society B.
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Oscar Manzi et al. 2026. Flexible self-defense as evidence of a pain-like state in house crickets. Proc Biol Sci 293 (2070): 20260609; doi: 10.1098/rspb.2026.0609
Source: www.sci.news
