Where Do Monarchs Get Water in the Winter? Backyard Observation Reveals a Clue Dew is sometimes the only water monarchs can find! The monarchs are in Mexico during Mexico's dry season. Dew is important for thirsty monarch butterflies.   Dr. Calvert's Observation in Mexico: In the early mornings, butterflies pour into the fields to drink. I have noticed that they concentrate on the sunny side of a shaded patch. They are clustered in a narrow band only 1-1.5 meters wide. They're drinking dew there, just before it evaporates in the strong tropical sun. The monarchs can't seem to function well in the shade, so they move in this narrow band of sunshine where the sun hasn't evaporated the dew yet. By noting whether dew or frost is present, we know if this important source of water was available to the monarchs that day. As the dry season progresses, the dry air dries out the forest and the butterflies. The wind, and the lack of moisture in the ambient air, dries them quickly. Dew is often no longer available. The monarchs have to go down to streams (and to nectar, if available).    Copyright 2005 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to jn-help@learner.org