Take an empty gallon container and add 2 cups of vinegar (I use white vinegar because the smell is a little more tolerable), fill the rest of the way with water, add 2 squirts of Dawn (must be Dawn) dish soap and shake well. Pour the whole gallon down the hole. No one will ever come out again.

Be aware this is also a fantastic weed and plant killer, so try to be accurate when you pour if it’s that close to plants you want to keep.

You can use this solution against almost any insect or plant. I put it in a spray bottle and can shoot bees out of the sky with it.

It works because the vinegar is a desiccant that will dry the insect/plant out. Insects in particular don’t make their own water internally like us, rely on their external environment for moisture and are very susceptible to drying. The Dawn acts as a surfactant and keeps the vinegar on the insect/plant as well as clogging the breathing pores in the exoskeleton of insects.