Researchers from Clemson University in the United States have uncovered a fast-acting protective mechanism in caterpillars. When injured, these larvae can cause their hemolymph, the insect equivalent of blood, to halt leakage within seconds. The finding holds promise for new medical approaches to stopping bleeding in humans and was reported in a study published in Boundaries in Soft Matter.
The team examined tobacco hornworms, sizable caterpillars that can grow up to about 10 centimeters. They induced shallow cuts on the limb-like pseudopods and collected the leaking hemolymph to observe how its condition changed in real time. The goal was to understand the sequence of events that enables rapid wound sealing at a microscopic level.
Immediately after injury, the hemolymph is a fluid similar to water. Yet within roughly five seconds its properties shift dramatically: it becomes viscoelastic, taking on a gel-like quality comparable to mucus. The caterpillar then retracts the liquid into its body and closes the wound with a coating formed by hemocytes, the immune cells present in hemolymph.
Further observations showed that the hemolymph behaves like a low-viscosity Newtonian fluid at the moment of injury, with its viscosity and elasticity changing as it is stretched or drawn into the body. This dynamic change enables a rapid transition from a liquid to a protective solid-like layer at the wound site, reducing bleeding powerfully and quickly.
To dissect the cellular and physical processes behind this response, the researchers employed a combination of optical phase contrast and polarization microscopy, X-ray imaging, and materials modeling. These tools helped reveal how hemocytes gather and reorganize to form a crust-like crust that seals the wound. The same mechanism was observed across multiple insect species in the study, indicating a conserved wound-healing strategy in insects.
The scientists emphasize that this fast, bio-inspired response could inspire the creation of new drugs or materials capable of turning human blood into a gel in a matter of seconds to stop bleeding more efficiently, potentially improving outcomes in emergency medicine and surgery. By translating the natural mechanism into medical technology, researchers hope to develop safer, faster ways to control hemorrhage in critical situations.
In related work, researchers have explored how natural biological processes can inform environmental and waste-management solutions, including efforts to engineer organisms or systems that address plastic waste. While those projects differ in their aims, they share a common thread with the caterpillar study: leveraging insights from biology to design innovative, practical solutions for real-world challenges.
The broader implication of these findings is to highlight how a simple yet rapid shift in the physical state of a biological fluid can have outsized effects on healing. The work demonstrates a clear example of how cellular components, when mobilized and organized quickly, create a robust barrier against further injury. This integrative view—from microscopic cells to macroscopic outcomes—offers a new perspective on wound care and the engineering of bioinspired materials for medical use.