Some of the insects and pests we deal with won't be deterred by a pair of panty hose. Prevention is the key. Don't go cut your grass and come in and visit garden before showering and changing. Keep a clean grow room. If you have pets, be religious about their Advantix or insecticide applications.
You'll never come up with a mesh tight enough that won't restrict water, light and air , but will stop bugs.... The idea is to prevent conditions that favor bugs.