Protected Cropping
The mesh that stops whitefly is the mesh that turns your greenhouse into a sail. Those are the same property measured twice.
— kN
Wind load the screen transfers into the structure
The drag relation is the classic screen result for flow forced through the mesh, and it is an upper bound: at high load a real screen deflects, spills flow around its edges and sheds part of what this predicts, while a taut screen on a rigid frame gets close to the full figure. Exclusion depends on the smallest opening dimension rather than the nominal mesh count, so a rectangular hole is only as insect-proof as its narrow side — the figure to compare against a thrips or whitefly thorax width. The load computed here is a wind action for a structural engineer to check the frame and anchors against, not a verdict on whether they are adequate.
Insect Mesh Porosity vs Wind Load Drag Force — free, with the formula and a worked example, at Textile School.