The insect mouthparts are used to pierce the grain through one of the pores, and the contents are extracted without swallowing the grains. There appear to be two primary paths by which pollen-feeding has been arrived at, evolutionarily, by insects. One is via carnivory, and in particular, feeding on other insects. Because it is a rich source of protein, pollen is nutritionally much more similar to insects themselves than it is to non-reproductive plant parts. The second path is that taken by phytophagous insects which come to feed on the flowers of plants, instead of on foliar tissue or other parts.
Some insects are general florivores, while others are specialized to pollen or ovules.
In many cases it is thought that masarine wasps are effective pollinators of the plants they visit. Insects that eat pollen. Required papers Wcislo, W.T., and J.H. Cane. 1996. Muller, A. 1996. Full references list General References Baker, H.G., and I. Baker.