Deleting and inserting rows

Try these

Range(Cells(5, 1), Cells(8, 1)).EntireRow.Insert Shift:=xlDown

Dim I As Long

Application.ScreenUpdating = False

For I = 151 To 3 Step -2
Cells(I, 1).EntireRow.Delete
Next I

Application.ScreenUpdating = True

VBA Noob