Mosquitoes bite through light wind shirts made of materials such as Pertex Microlight. Permethrin, put on after any DWR, cuts the DWR effectiveness in about 1/2. Permethrin put on before the DWR cuts the DWR effectiveness to about 0.
It appears that you have to make your choice as to whether you want to be dry or bug free but the ultralight combination is not easily attainable.
This would be a good BPL topic for Jordan.