How effective are our current control methods for Argentine ants? Melissa Mathieson has just published an article suggesting varying efficacy for pesticides to New Zealand populations of this global invader. She showed that even the most effective pesticide, Xstinguish, was less effective in controlling queens in an ant nest compared to workers. Queen mortality in a nest ranged from nil to extremely low when the ants were starved for only 24 hours. The pesticides failed to kill all queens even when nests were completely starved for 48 hours. These results agree with our field observations. Commonly we’ve observed ants to survive or reappear very quickly after pesticide treatment. This reappearance may be from reinvasion or from the survival of treated colonies as this study suggests.