Artificial night lights might accelerate the growth of monarch butterflies. While street lamps and other sources of human light may confuse the migration routes of birds, sea turtles and other creatures, new experiments on insects reveal the complexity of responses among wildlife. For two years, scientists exposed monarch caterpillars (Danaus plexippus) to white LED streetlights at night. They found that caterpillars under lights had a 16% higher growth rate than those that weren’t exposed to night light. They also took less time to develop into adults. Caterpillars raised on one kind of milkweed had 7% larger wings than those experiencing darker nights. The researchers believe that the monarchs grow faster by accelerating their investment in early development. “Our findings underscore that light pollution at night alters the entire developmental trajectory of these holometabolous insects, highlighting its strong capacity to reshape insect life histories in the Anthropocene,” the authors said in the study.
