I would think that nylons would be a relatively effective barrier against ticks at point of contact, but if the tick migrates to a spot not so covered he will burrow in there instead. Ticks have to kinda gnaw their way into ya, and it can take them a bit of time. Most flies are the same, though my experience is a big horse fly might be able to get through nylon armor with those mandibles of his. Fleas likewise ought to be able to chew their way through nylon, but they get into other places too easy to consider the deterence factor nylons would have on them. Mosquitoes and sandflies have a hypodermic extension that allows them to penetrate the weave if it isn't too thick, so nylons probably aren't going to do a darned thing for them. I find a combination of deet and a pre-emptive dosing of B-complex to be most effective on most biting insects like these.

Mosquitoes can make it through flannel, but not flannel and thermals. I don't think nylons have enough loft to separate the outer layer from your skin far enough.

For less than $100 you can build an ultrasonic sweeper that will drive most all biting insects far away. Nothing like 80 db at 19 to 35 Khz to really knock the skeeters outta the air. Of course, you're not gonna see much game using that device either, but at least you can enjoy the woods relatively bite free with it.