Honeybees pollinate squash and zucchini. If there are not enough bees present in your neighborhood, the flowers don't get pollinated, and the small fruits wither and die. Without bees, the only way to pollinate those flowers is by hand. You can use a small artist's paintbrush to transfer pollen, or you can break off the male flower and roll it into the center of the female flower. Female flowers can be identified by the miniature fruit at the flower base.
Flowers open early in the morning and are receptive to pollination for only one day.
Another alternative is to include plants in your garden that are attractive to bees. English lavender, Lavandula angustifolia, and Butterfly Bush, Buddleia davidii, are honeybee magnets. When buying bare-root roses, the branches come coated with a waxing substance. Before being shipped from the grower for sale, the branches of bare-root roses are in fact coated with wax to prevent the canes from drying out, says UC master gardener Janine Jacobs. You should not remove this protective layer before planting.