Question

the pitcher plant is green and can photosynthesis then why does it feed on insects ?

Answer 1

every plant need some amount of nitrogen for nutrition , pitcher plant grows in nitrogen less or soils which r deprived of nitrogen therefore that some amount of nitrogen the picther plant gets nitrogen frm those insects and fulfils its need of nitrogen !! :) 

Answer 2

the soil in which pitcher plant grows have no nitrogen so for gaining nitrogen it feeds on insects.......................