I have about 80 cicada killer wasp nests in my front yard. I have tried all remedies that I have seen on the internet and have had no success
Cicada killer wasps, as you might know, are large wasps that catch cicadas, paralize them and bury them in the ground, then they lay their eggs and the cicadas are the food for the developing wasp. To be effective you should do the treatment in the evening when the wasps are in the holes, not when they are flying around. You don't say what you have tried. The most environmentally effective way is to carefully without burning yourself, pour almost boiling water in each hole. This might be very difficult if you have lots of them. Or put a good dusting of a product called Sevin in the holes, or pyrethrin-containing porducts. Ideally you then cover up the hole. This doesn't kill them right away but will eventually. Or if all else fails try spraying in each hole with a wasp/hornet spray. Wear gloves, mask, goggles and cover yourself up. This will be tedious but should work, even if it isn't environmentally friendly. It is best to use new spray as if it has been sitting around a long time it looses effectiveness.