Bithor Insecticide is new chemistry for spiders and other persistent pests. It combines the power of imidacloprid (a neonicotinoid) with a pyrethroid (bifenthrin). This “dual action” synergy is much more effective that either insecticide alone, the company says — and has more than two times the residual control of pyrethroids on insects that breed quickly in the summer heat, such as ants, mosquitoes, cockroaches and fleas. Bithor is labeled for more than 100 pests outdoors and indoors. In addition, it is approved for general turf and ornamental applications. It’s packaged in easy-to-manage quarts (pictured) and gallon containers.