Demon WP needs to be used within 24 hours of mixing. The product will likely lose its efficacy if it is left inside the sprayer.
You can use Demon WP Insecticide and Invict Gold or another cockroach bait gel in the same treatment rooms, however you want to avoid spraying on top of bait placements or in areas where you are going to place baits. Your general rule is to SPRAY LOW and BAIT HIGH. To mix the Demon WP, you should use 1-2 packets per gallon of water, so if you were to use less water, you should still use at least 1/2 gallon of water for 1 packet. You could also choose a ready-to-use product instead of a concentrate so that you do not have to worry about mixing correctly. We sell a new product called Dos Flea and Crawling Insect Spray which contains both an insecticide and an IGR for control of roaches and other listed insects. Please see our Roach Treatment Guide for more tips and information.
Yes, Demon WP Insecticide can be tank mixed with an insect growth regulator. Just be sure you always follow the manufacturer's labeled mixing instructions for each product.