Argentine ant (Linepithema humile).
These small ants are 2-3mm long. They are a brown/honey colour, and have no smell when squished. They often travel in long foraging lines 3-5 ants wide. Argentine ants don't like noise and when disturbed will swarm out of their nest. Once a nest has been disturbed, its multiple queens will usually relocate, moving off to form several new nests.
Argentine ants are ranked among the 100 most invasive species on earth.
They threaten native insects, lizards and birds either by predation or competition for resources. Though not poisonous, their bites can irritate and cause allergic-type reactions in some people.
Nests have multiple queens and are capable of multiplying into huge numbers in a very short time. While their natural spread is around 150m per year, Argentine ants also spread much further afield by hitching rides in things like pot plants, dirt, building materials, camping equipment and caravans.
Having arrived in New Zealand in 1990, Argentine ants have now spread across Northland and many other parts of New Zealand.
Argentine ants can be difficult insects to control and should not be treated as ordinary ants. Contact a qualified pest control agent. Special sprays are needed, which can only be handled by qualified contractors (over-the-counter ant control solutions don't work on Argentine ants).
Ensure soil potted plants, outdoor equipment or other mediums which could contain ants are ant-free before moving these to other areas. If you suspect you have Argentine ants you can get them identified by delivering a sample to a Northland Regional Council office. Ant samples should be put into a screw-top container and frozen.