The cenchrus (plural cenchri) is a specialized anatomical structure in the

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three ...

group known as

sawflies Sawflies are the insects of the suborder Symphyta within the order Hymenoptera, alongside ants, bees, and wasps. The common name comes from the saw-like appearance of the ovipositor, which the females use to cut into the plants where they lay ...

. The cenchri are small blister-like lobes on the

metanotum The metathorax is the posterior of the three segments in the thorax of an insect, and bears the third pair of legs. Its principal sclerites ( exoskeletal plates) are the metanotum (dorsal), the metasternum (ventral), and the metapleuron (lateral) ...

of these insects, just posterior to the mesothoracic scutellum, shaped and positioned in such a way as to latch onto the base of the front

wings A wing is a type of fin that produces lift while moving through air or some other fluid. Accordingly, wings have streamlined cross-sections that are subject to aerodynamic forces and act as airfoils. A wing's aerodynamic efficiency is expre ...

when they are folded at rest. There are corresponding small patches on the wings where the membrane is roughened, to increase the friction against the dorsal surface of the cenchri. This is a unique mechanism among the insects.

References

Sawflies Insect anatomy {{insect-anatomy-stub