Self-pollination is certain in flowers due to which the lineage of plants continues.
In self-pollination, more pollen grains are not required, hence pollen grains are not wasted.
The seeds produced by self-pollination are fewer in number, lighter in weight, and smaller in size.
In cross-pollination, pollen from one flower reaches the stigma of a flower of another plant of the same species. Here both the flowers grow on two different plants, whether they are unisexual or bisexual.
The fruits formed from cross-pollinated flowers are very heavy and tasty and contain a high number of seeds.
To attract insects, flowers have to produce bright colors, large petals, fragrances, and nectar, all of which lead to the wastage of a lot of material and loss of a lot of energy.