We typically only did one ounce to a gallon. I use these water soluble packets and just do one in a gallon sprayer of water. Demon WP Insecticide 1 Envelope Containing 4 Water-Soluble 9.5 Gram Packets Makes 4 Gallons Cypermethrin 40% https://smile.amazon.com/dp/B00E355QOI/ref=cm_sw_r_cp_api_glt_fabc_Y5CKZJ43VXDV3C2M2S0Z
With any sprayer, be sure you rinse it out thoroughly after, and then pump and spray clean water through it too to finish cleaning it.
Get you some WP Demon. This will do the trick. I swear by it. https://www.amazon.com/dp/B00E355QOI/ref=cm_sw_r_cp_awdb_J6jUzbPW9YGAJ