milkweed flower above milkweed plant used as graffiti for monarch butterflies

Directing monarch butterflies
to urban food sources along migratory routes in North America

GFB uses images of milkweed flowers to broadcast the location of food sources to monarch butterflies. In the prototype at left, the graffiti is placed on a wall above an actual milkweed plant in New York City, signaling the presence of nectar to hungry monarchs in the vicinity.

Monarchs regularly pass through wide swathes of human settlement as they migrate each year from wintering sites in Mexico to summering grounds in the United States and Canada. GFB is the equivalent of a fast-food sign on a highway, advertising rest stops (waystations) to monarchs traveling through the area.

sunblock spray used as spraypaint for graffiti for butterflies

Optimizing the graffiti for butterfly vision

Milkweed flowers have natural ultraviolet (UV) patterns that are recognizable to monarch butterflies. These patterns are invisible to us because we can't see light in the ultraviolet spectrum. So GFB uses sunblock to paint the graffiti in a way that mimics these natural ultraviolet properties. (Sunblock is perfect for this, because it's designed to reflect ultraviolet light away from our UV-sensitive bodies— it's essentially a cheap and easy UV spray paint.)

Painting with sunblock

The head (corona) of the graffiti flower is sprayed with sunblock to produce a burst of color in the ultraviolet spectrum. The video is an approximation of monarch butterfly vision— it's not possible to accurately represent the color of ultraviolet light in the spectrum visible to humans.

A monarch feeding on a balcony in New York City

The monarch in the video at left not only fed on this milkweed— it also laid some eggs, which soon hatched into tiny hungry caterpillars. The milkweed plant is the monarch caterpillar's sole food source.

See the photos: Caterpillars in the City

Comments
  1. Enid
    July 2nd, 2008

    Elliott…this is fantastic. And I loved seeing your bar mitzvah. but aren’t milkweed blossoms a pinkish color?…this looks orange.

  2. FilipFilip
    August 1st, 2008

    Pretty cool story for an old graffiti head like myself… Have you considered creating a library of “graffiti” flowers for New York State butterflies and moths? How about a list of butterflies and where to get the seeds for their host plants… (butterflies populate over 75% of our plants, and only ever nest on one ‘host’ plant).

  3. asha
    August 4th, 2008

    That is really cool. Sometimes people just blow my mind.

  4. Dr. Ronald Rutowski
    April 28th, 2009

    Here are a couple of my thoughts stimulated by this idea.

    1) Many flowers vary across the surface of the petals in how much UV light they reflect. The resulting patterns are invisible to our naked eye, but most nectar feeding insects can see them. This means that different parts of the flowers are perceived by insects as being different colors, and insects do use these UV patterns to recognize and orient to flowers. Do milkweed flowers have such UV patterns as is claimed on this page? I could not find any images on the web to confirm this and none is provided on the web page.

    2) Contrary to what is suggested on this web page, sunscreen works by absorbing, not reflecting, UV. Chemicals in the sunscreen absorb UV light thereby preventing it from reaching and burning our skin. Making a sign or coating a flower with sunscreen would make a surface that would reflect very, very little UV, which would also change its color to an insect.

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