The Halifax Regional Municipality is warning residents about a foreign menace that's making life difficult in some backyards.

The European fire ant is an invasive insect that aggressively defends its territory, even stinging humans and pets. The ants nest in soil, under rocks and in decaying logs, and spread easily.

The HRM said there are fire ant populations in the Summit Street and Jubilee Road areas on the Halifax peninsula, and in Spryfield, Lower Sackville, Abercrombie and Stellarton.

The parks division will manage infestations on municipally owned parkland, but the HRM has said residents will have to take care of the problem themselves.

The reddish-brown worker ants are about five millimetres in size. The middle part of their bodies is divided into two sections, and two backward pointing spines are visible with a magnifying glass.

The ant is known to be present in New Brunswick, Quebec, Ontario and the northeastern United States.