my @filenames = parse_dir($ls);

foreach (@filenames) {
    my $mtime = (stat($_))[9]; # Get mtime for file
    my $year = (localtime($mtime))[5] + 1900; # Get year for file
    my $month = (localtime($mtime))[4] +1; # Get month for file
    my $day = (localtime($mtime))[3]; # Get day of month for file
    if ($month >= 03 and $year == "2013") {
         if ($month == 03 and $day >=20) { print "Filename: $_\n"; }
         if ($month == 04 and $day <=21) { print "Filename: $_\n"; }
    }
}