Insect-proof mesh is offered in pre-cut sizes, a variety of widths and any length can be ordered ‘off the roll’. The larger the sheet and the closer it is to manufactured sizes the less it costs per square metre.
Mesh is also sold in varying mesh sizes. The smaller the mesh the smaller the insect excluded but the greater the cost and also potential increase in temperature (finer meshed insect proof material may lead to a significant warming for the covered crops) and humidity beneath. On the other hand finer meshes tend to be lighter and easier to use without supporting hoops.
Standard mesh: 1.3-1.4mm Good for soil pests such as cabbage root fly, onion fly, bean seed fly and carrot fly, as well as moth and butterfly pests. Birds and mammal pests are also excluded. Although theoretically capable of penetrating mesh, mammals and larger birds seldom do, so there is rarely any need to add further protection such as bird netting. However, they are unreliable in excluding small insects such as aphids, flea beetle, allium leaf miner and leek moth.
Fine mesh: 0.8mm Good for very small pests such as flea beetles and whitefly, moth and butterfly pests, leaf miners (including allium leaf miner), greenfly, blackfly, as well as soil pests such as cabbage root fly, onion fly, bean seed fly and carrot fly. Birds and mammal pests are also excluded.
Ultrafine mesh: 0.3-0.6mm This size gives good protection against thrips, flea beetles and other very small pests. Birds and mammal pests are also excluded.
Butterfly netting: Fine nets with a 4-7mm mesh give good protection against cabbage white butterflies as long as the foliage does not touch the net, and of course bird and mammal pests.