We use artificial glass feeders to blood-feed mosquitoes that are located within a cage. The mosquitoes have to land on and feed through the fabric to get to the blood and are so exposed to it.
We measure engorgement rates to determine repellency effects of the fabric treatments. If mosquitoes take blood the fabric treatment was not effective. We can also measure survival rates over time in case the fabric is treated with pyrethroids or other insecticides.
The results of feeding assay experiments can be used the efficacy of specific treatments for clothing, bed nets, etc.