Technical Abstract: Weekly and biweekly sweep net collections were made near Blairstown, NJ and Newark, DE for 12 and 6 consecutive years, respectively. In New Jersey, only one non-native coccinellid (C. 7-punctata) species was common when this research was started in 1993, one (P. 14-punctata) had recently appeared, and two other foreign species (H. axyridis, H. variegata) were detected later during the 12-year study. All of these four species were adventive, having established themselves through commerce, three species at inland ports, and one near a coastal seaport. The most numerous adult lady beetles at both locations were two native species, Coleomegilla maculata, and Hippodamia parenthesis, and three adventive species, Propylea 14-punctata, Coccinella 7-punctata, and Harmonia axyridis. Six species were occasionally swept at Blairstown--one adventive species (H. variegata) and five native species (Cycloneda munda, Coccinella transversoguttata, C. trifasciata, Hippodamia convergens, and Brachiacantha ursina). All but the last species were also found at Newark. Lady beetle numbers varied considerably from year to year at both locations, demonstrating that long-term (10 years or more) research is required to correctly identify population trends. No coccinellid species decreased during the 12 year study in New Jersey--indicating that the once-common H. convergens and several Coccinella species had become rare before the study started in 1993, and before three of the four adventive lady beetles had become numerous. The previous establishment of exotic parasites, which reduced pea aphid numbers, was likely responsible for decreasing coccinellid diversity in alfalfa. It is possible that competition by the adventive C.7-punctata also reduced some coccinellid species, but such data for the northeastern U.S. have not been published, to our knowledge.