Emilio Jorge Powers wrote, "I wonder why the Euglandina wipes out the Achatinella and Partulina (native Hawaiian tree snails) etc etc on the Pacific islands yet they do not seem to make a dent on the Liguus populations in South Florida. The Euglandinas are native to Florida and SUPPOSEDLY were here before the Liguus arrived." Good question. Let's take an analogous case. Suppose that humans were native to the Old World and then a few couples were moved to a Pacific island, where they prospered at the expense of the native fauna. Since no small part of a group could carry all the diseases and parasites of the larger ancestral group in the Old World, the islanders must have started out with only a few kinds of disorders. Also, the survivors of the rigorous voyage are likely to have been fairly healthy. The result is that the islanders might have herpes and the common cold, but lack leprosy and measles. I suspect that the Florida Euglandina have diseases and parasites that we know little or nothing about, and which help to keep their population down there. In Hawaii, they have only a few disorders and little to stop their spread. Of course, this is only one factor. Euglandina may have carried new diseases to the snails of the island. Their prey may have no effective defenses, such as hiding, being active at a different time of day, or tasting bad. We don't know, but if we did, we might be able to stop Euglandina in its tracks--er, trail. More likely, however, we may discover that nothing can be done but to culture the native snails in a giant terrarium. Is anyone doing that, by the way? Andrew K. Rindsberg Geological Survey of Alabama