Vogtia malloiPastrana was introduced into the United States from Argentina in April 1971 as a biological control agent of alligatorweed,Alternanthera philoxeroides(Mart.) Griseb.Vogtiawere released at 10 different locations from Wilmington, North Carolina, to Ft. Pierce, Florida. Populations have become established at four of these release sites. Population studies conducted at the Lake Alice release site, on the University of Florida campus, Gainesville, Florida, indicated the new population dispersed randomly over the stand of alligatorweed.Vogtiareduced the number of aerial alligatorweed stems per square foot from 52.5 to 4.0 in four generations. The alligatorweed did not have a competitive advantage by the end of the fourth generation; mixed vegetation was replacing the deteriorating mats of alligatorweed.