Do flowers need insects to pollinate them?

Not all flowers require insects for pollination.

Most angiOSperms (flowering plants), in particular dicotyledonous plants, require an agent of pollination; normally these are animals - mainly insects, but can also be birds, mamals, centipedes etc.

Monocotyledonous angiOSperms which comprose largely of grasses are pollinated mainly by wind.

Gymnosperms (cone bearing plants) rely mainly on wind pollination and therefore produce large quanitites of pollen.