Reproductive swarming phenology, swarm sizes, and cavity selection were studied in a European-derived population of Apis mellifera L. in southeastern Louisiana before and immediately after the initial detection in 1992 of Varroa destructor Anderson & Trueman (Acari: Varroidae). Frequency of swarms was highest between early April and early May in each of 6 yr. Swarm weight averaged 1.42 kg (range 0.17–4.30 kg) and did not change significantly the year after detection of V. destructor. Swarms spent an average of ≈20 daylight hours scouting for a new nest-site from a temporary location and moved more frequently to cavities of 30-liter than to those of 13-liter volume. Swarms were random in direction of movement. Dance tempos at the time of swarm departure indicated movement to cavities at distances from 200 m to ≈10 km. The genetic composition of this honey bee population is likely to change after natural and artificial selection for resistance to new parasites, such as V. destructor and Aethina tumida Murray (Coleoptera: Nitidulidae), and as Africanized bees expand their range. Swarming characteristics are also likely to change both from direct effects of parasites on colony reproduction, and by changes toward bee populations with differing life histories.