Core Points - Residents in the eastern Mongolian region, including Manzhouli and Genhe, reported a significant presence of large ants, approximately 2 centimeters in length, raising concerns about potential invasiveness [1] - An expert identified the ants as likely being the Japanese arch-backed ant, which is not an invasive species in China but is widely distributed across the country [2] Group 1 - The large ants observed are likely the Japanese arch-backed ant, which can grow to a length of 12.3 to 13.8 mm for large workers and 7.4 to 10.8 mm for medium and small workers [1] - The presence of these ants is linked to environmental conditions, with drought limiting their activity and increased activity noted before and after rainfall [2] - The reproductive phase of ants, known as nuptial flight, occurs in spring and summer, explaining the sighting of winged ants [2] Group 2 - The impact of the Japanese arch-backed ant can vary based on context; it can be beneficial in controlling pest populations like the pine caterpillar or harmful if it disrupts public spaces [2] - Decisions regarding pest control should be context-specific, assessing whether the ants are beneficial or harmful in particular situations [2]