Because of exhaust gases, insects can no longer find their way to the flower - but you can still attract butterflies. Grow plants in your garden that provide food for nocturnal insects and thus increase the supply of the animals.
These include evening primrose, perennial phlox, moon glories, evening evening violet, honeysuckle and many more species. Many moths feed on rotting fruit, but there are also plants that only open their flowers to insects at dusk and exude a tempting scent.