fine mesh as grillblock?

[lunarhighway]

what would the effect of a fine mesh, like the kind used in flydoors etc, on the airflow and drag.
A while ago i came accross an article on ecomodder where someone sugested useing a perforated sheed as a grillblock where the perforations made up roughtly 30% of the total area. Most people sugested useing a solid sheet and leave 30% uncovered if that was needed. but one guy said there was a difference, as at higher speed small holes would "close up" and the whole thing would appear as a solid sheet to the oncomming airflow. This actually seems rather possible... toyota actually used perforated plates as a grill on their previous models of the corolla and the yaris... whatever the reason for that choise, it proves it's possible.

This combined with the fact that a lot of bugs find their final restingplace spached in the radiator (wich i imagine might be a slightly bad thing for the airflow trough it) got me thinking what the effect of a flyscreen on the overall airflow would be... Would this pervent some air from getting trought the radiator and direct it over the car, or would it add aditional drag? Fly doors can be blown open by the wind so they probably represent more resistance than their appearance would sugest.

i'm mainly interested in this as it seems to offer the best of both worlds, a fairly open grill at low speed and slow traffic where full grillblocks might become a problem and a solid front at high speeds where a small fast airflow allows for adequate cooling.