Why isn’t your shirt all mesh?
Mesh is mostly holes between the woven or knit fibers. Consequently anywhere the mesh is in contact with your skin, mosquitoes in particular have easy access to your blood supply. We use a specially constructed high density protective fabric (either cotton or polyester), which mosquitoes are not able to penetrate, because it eliminates the need to wear extra clothing underneath in order to be protected. It is also more comfortable since mesh can be quite abrasive against bare skin. It is usually warm when biting insects are active so we use the mesh just for ventilation providing ultimate protection as well as cool comfort.