Fipronil

They are vulnerable to some pest control poisons — Mr. Rasberry uses products containing the chemicals fipronil and chlorfenapyr — but given the ants’ staggering proliferation and environmental restrictions on the products, not enough of the chemicals can be put down to make a difference, Mr. Meyers said.

He thinks new classes of insecticides introduced in the last 20 years, including neonicotinoids and fipronil, have been particularly damaging as they are used routinely and persist in the environment: “They sterilise the soil, killing all the grubs.”