True, bees have little food when there are no flowers. Remember that bees feed on nectar, which directly comes from flowers.
However, they can also get the same from fruits, such as oranges, pineapples and mangoes, or even sugar.
This is why it is common to see bees buzzing over sugar bowls. So, if you want to feed them artificially, cut fruits and place them near the beehive.
Alternatively, build a hive that has a hole below, through which bees can pass to access a container filled with sweet fruits, such as mangoes and oranges.
The bees will drop from the hive into the container to get food from the cut fruit parts. Also, remember that bees need water to create honey.
Therefore, place some water nearby during the dry season. You can strategically place small containers of water near the bee hives.