Crossveins

Crossveins are small wing veins that connect the major longitudinal veins in the wings of many insects, forming part of the wing venation pattern. They contribute to the structural integrity of the wing and influence how the wing deforms and generates lift during flight.

In insect wings, the principal longitudinal veins include the costa, subcosta, radius, media, and cubitus, with additional anal veins near the wing base. Crossveins are typically named by the veins they join, for example the r-m crossvein connects the radius and media, and the m-cu crossvein connects the media and cubitus. Several series of crossveins may occur, and their presence, absence, or arrangement can vary widely among taxa, providing important diagnostic characters for classification and phylogeny.

Functionally, crossveins help partition the wing into closed cells, aiding rigidity and strengthening the wing against bending during rapid or powerful flight. They also influence the wing’s aerodynamic properties by shaping the wing margin and surface tension. The pattern of crossveins can reflect evolutionary history, with more complex patterns typical of some fossil groups and certain extant lineages, while others show reduced or fused crossveins.

Variation is common across insects: some groups retain numerous crossveins, whereas in others they are sparse or lost through evolutionary change. Because crossvein patterns tend to be relatively conserved within lineages, they are frequently used in taxonomic identification and in studies of insect paleontology.

In botany, the term crossveins also appears to describe secondary veins in leaves that connect major veins, contributing to the overall leaf venation network.