Also called entomophily, insect pollination is a form of pollination whereby pollen of plants, especially but not only of flowering plants, is distributed by insects. Flowers that are pollinated through this method usually display morphological features and behaviors aiming to attract pollinators via bright colors, strong scents and other conspicuous patterns (nectar guides). Nectar guides, which are only visible to certain insects, facilitate pollination by guiding pollinators to the pollen at the center of flowers. The symbiotic relationship resulting from the coevolution of insects and flowering plants benefits both groups, allowing plants to be pollinated and insects to obtain valuable sources of food.
Insect pollinators notably include bees, flies, wasps, butterflies, ants, beetles, and moths, the latter being mainly attracted to pale and flat flowers that are open during the late afternoon or night. Bees are unequivocally the most important pollinators of many garden plants and fruit trees and are therefore of critical importance – even more so as their population has been alarmingly declining over the years. The two most common species of bees are bumblebees and honeybees. Like butterflies, they visit flowers displaying attractive characteristics, typically with a tubular shape and the presence of a nectar guide. The pollen sticks to the bees’ fuzzy hair (or limbs in the case of the butterflies), which will be transferred to the second flower during its visit. The nectar provides energy while the pollen provides protein.
Pollen grains of entomophilous plants are generally larger than the fine pollen of anemophilous (wind-pollinated) plants, which has to be produced in much larger quantities because of the unpredictable nature of its deposition. This is energetically costly, but in contrast, entomophilous plants have to bear the energetic costs of producing nectar.