Argentine ants in Melbourne: why they flood back every spring and what stops them

Short answer: Argentine ants come back in spring because the colony that sheltered underground through winter starts foraging again as the soil warms, and in Melbourne their nests link up into super-colonies that cover whole streets. Spraying the trail you can see kills a few hundred workers and leaves thousands of queens untouched.

How to tell it's Argentine ants:

- Small (2 to 3 mm), light to dark brown, all the same size. - Trails are dense and fast, often in a double line along skirting boards, window frames and power cables. - They don't sting and don't have a strong smell when crushed. - They often appear after rain or the first warm week of October.

What doesn't work: surface sprays and most supermarket baits. Repellent sprays break the trail and push the colony to split, so you get two nests instead of one.

What works: a non-repellent perimeter treatment around the outside of the house, gel bait placed on the active trails inside, and finding the nest points in garden beds, paving joints and wall cavities. Workers carry the product back and share it through the colony, which is how the queens are reached. Most kitchens are clear within 48 to 72 hours.

If you share a fence line with neighbours who also have ants, tell us. Treating the boundary on both sides gives a much longer result.

Ant treatments start from $89 and come with our written 6-month guarantee. Call 0436 122 195 or send a quote request and we'll give you a price the same day.