The best way to increase mushroom yields and decrease the damaging presence of sciarid flies? Apex®, the mushroom industry's pest control standard. Like many products manufactured by Wellmark International, Apex contains methoprene, the insect growth regulator (IGR) that stops the development of immature sciarid flies before they become destructive adults. No wonder it's been used on 60 million square feet of mushroom farms across North America.