Rachael Winfree, a professor in the Department of Ecology, Evolution, and Natural Resources in the School of Environmental and Biological Sciences at Rutgers University-New Brunswick conducted a study of 131 farms across the United States and in British Columbia Canada.
The team of scientists collected data on the insect pollination of crop flowers and yields for apples, high bush blueberries, sweet cherries, tart cherries, almonds, watermelons and pumpkins. They found that apples, sweet cherries, tart cherries and blueberries showed the most decline in fruit yields. Wild bees and honey bees are the main pollinators for these crops.
This is directly related to the decline in pollinating insects, primarily bees of all types. Homeowners can contribute to the increase of these insects in a variety of ways. You do not need a large area to plant bee and pollinating insect flowers. Also avoid using insecticides.
I maintain gardens around my home that produce flowers from early spring to late fall. Besides Butterfly bushes, you can plant Coneflowers, dwarf flowering bushes such as My Monet Weigelia, and dwarf Crepe Myrtles. These are some suggestions for small areas that attract butterflies, bees and other pollinating insects. The advantage of having Coneflowers is that if you do not deadhead them and leave the flowers on the plant until spring, the birds love the seeds in the fall and winter. Some of these plants can be grown in containers.