When do bees and butterflies collect nectar?

They come out in the early spring (for me they do) and stay here until it gets cold, which is in about october. It is still hot where I live, and the mournings are freezing but then it gets so hot. From about june-october, more or less. You can't be accurate. All seasons are different and the climate length and warmth are also a varying option to when they would come and go.