Those are the results of a nationwide bee survey conducted by every day citizens, according to a news release.
Gretchen LeBuhn, a San Francisco State University biologist, coordinated the survey.
She plans to take it a step further on Aug. 11 by urging residents throughout the country to count bees in their yards and neighborhoods as part of a great bee count.
LeBuhn launched a program dubbed The Great Sunflower Project in 2008 to collect information about the decline of pollinators and the related ecosystems.
Part of the project involved 100,000 volunteers, who annually tabulated bees in their gardens and yards.
What she found was urban gardens have far fewer bee visits—23.3 bees per hour compared with 30.4 per hour in rural areas.
Her next goal is to compare rural, urban and suburban areas to see their effects on pollinators.
Growers rely on managed bees to pollinate many crops, including almonds and melons. Without bee hives, the crops would produce scant yields.