A note of caution
It is important to note that unless the specimen you are trying to identify was collected at a port of entry, a disturbed habitat with a limited native ant fauna, or a Pacific Island there is a strong likelihood that the species to which it belongs is not in the key. If you believe the species is non-native and you use the key for identification, make sure to check your determination against the specimen images and read the corresponding species page. If you want assistance with the identification, or want to confirm your determination, please post a message in the forum.
The Lucid key to invasive, introduced and commonly intercepted ants is an interactive, fully illustrated identification tool that allows you to diagnose over 100 species of synanthropic ants from across the globe. The current version of the key serves as an update to the Pacific Invasive Ant Key (PIAkey), and now includes nearly all non-native ant species that have have become established in the United States or have commonly been intercepted at US ports of entry.
Lucid keys are unlike traditional dichotomous keys. Rather than starting at the beginning and trying to find the single path for an accurate determination, Lucid keys allow you to start from multiple entry points, skip over troublesome questions, click on links and illustrations, and watch as the list of remaining species shrink to one. By using the 'best' button, the software algorithm will determine which available characters will best divide the remaining taxa into approximately equal groups, thus leading you down the most parsimonious pathway. For more tips on how to most effectively use the Lucid key, see the best practices page.
Perhaps the greatest strength of the Lucid keys is the integration of media. Images and links are attached to all the characters and taxa. The ant key uses line drawings to illustrate general character states, and uses specimen photographs to illustrate how those states are expressed by different species. A common misconception about Lucid keys is that each taxon must be scored for each character. The ant key, for example, refrains from scoring genera and subfamilies. These higher-taxon groups act as ‘containers’ which are defined exclusively by the scores of the species nested within them. Another practice is to score only taxa for which the given character is informative, and use the ‘unscoped’ feature on taxa for which the character is uninformative. When properly applied, the unscoped feature causes character choices to appear only when all remaining taxa are scored for those characters. Keys designed to unfold in this way protect users from being overwhelmed by an unmanageable number of character choices, of which only a subset are informative for the taxon of interest.