Question

Hiw do the bees know that which flower has nectar?

Answer 1

by smelling them usually they are attracted by the beautiful colours

Answer 2

The answer is


 some species of plants have flowers that undergo specific color changes when their nectaries are ready to produce the nectar.

A common group of flowers that noticeably (to both humans and bees) changes colors once the nectaries are ready is the Lantana genus (about 150 species worldwide).