<P> Starting in September and October , eastern and northeastern populations migrate from southern Canada and the United States to overwintering sites in central Mexico where they arrive around November . They start the return trip in March , arriving around July . No individual butterfly completes the entire round trip ; female monarchs lay eggs for the next generation during the northward migration and at least four generations are involved in the annual cycle . </P>
<P> Starting in September and October , eastern and northeastern populations migrate from southern Canada and the United States to overwintering sites in central Mexico where they arrive around November . They start the return trip in March , arriving around July . No individual butterfly completes the entire round trip ; female monarchs lay eggs for the next generation during the northward migration and at least four generations are involved in the annual cycle . </P>
when do the monarch butterflies return to mexico
when do the monarch butterflies return to mexico
November
November