Atlanta stands on a ridge about 1,050 feet up, south of the Chattahoochee River, and Wikipedia credits it with the densest urban tree cover of any major American city. Shade, leaves and close neighbors suit many pests.
Atlanta had 498,715 residents in 2020 and is the seat of Fulton County, though part of the city reaches into DeKalb County. The Chattahoochee River marks its far northwestern edge, while the downtown ridge reaches roughly 1,050 feet, the highest elevation among major cities east of the Mississippi. Wikipedia counts 242 official neighborhoods, from Midtown and Buckhead to Old Fourth Ward and Cascade Heights.
Climate does the rest. July highs average 90.1 degrees, about 50.4 inches of rain fall in a typical year, and winter brings only around 2.2 inches of snow, so January lows near 35.6 degrees rarely stop insects for long. Add the tree canopy, the 22-mile Beltline corridor and plenty of multi-unit housing, and wood, water and warmth sit close together.