If the number of mesh is too small and the mesh is rather large, insect-proof nets can not prevent pests well; conversely, if the number of mesh is too much and the mesh is rather small, it can prevent pests, but the poor ventilation will result in high temperature and too much shading, which is not conducive to crop growth.
For example, many pests, especially some harmful moths and butterflies, start to move into the shed in autumn. Because of the large size of these pests, farmers can use insect-proof nets with a relatively small number of meshes, such as 30-60 mesh.
But for more weeds and whiteflies outside the shed, it is recommended that according to the size of whiteflies, farmers can choose denser nets, such as 40-60 mesh, to prevent them from entering through the mesh.
For example, the most critical control of tomato yellow leaf curl virus (TY) is the selection of qualified nylon insect-proof nets. Normally, a 40-mesh that kind of insect-proof net for whiteflies control is sufficient.
It is advisable to use white anti insect net in spring and autumn because of the lower temperature and weaker light. Taking into account the shading and cooling, black or silver-gray nets are preferred in summer. In areas where aphids and viral diseases are severe, it is appropriate to use silver-gray nets against them.
Some farmers have reflected that many of the insect-proof nets they just bought have broken holes, so it would be wise to unfold nets and check them at the time of purchase.