Wednesday, January 5, 2011

Butterfly Roosting

The holidays are over. The crowds have gone home. It's cold outside. What better time to visit the warm, quiet Tropical Butterfly House? And this time of year, guests can observe an interesting phenomenon in the late afternoon.

Ever wonder if butterflies sleep? And if they sleep - where? It may seem like a simple question but it is one frequently asked by our younger guests. The answer is "Yes, butterflies typically sleep when the sun goes down and they often sleep in same species groupings.”

Next time you visit the Tropical Butterfly House in the dead of winter, drop by at the end of the day before Pacific Science Center closes. Because the sun sets early this time of year, you should have a good opportunity to see butterflies roosting. Look up high in the treetops and under leaves. Sometimes you'll see mixed species sleeping together but most often a specific species will take over a limb or an entire plant.

For more information and to view a short video about butterfly roosting at the Reiman Gardens of Iowa State University go to


  1. How do we know the butterflies are sleeping? They can't close their eyes.

  2. We do not know for sure that butterflies sleep. However it has been determined that other insects, such as fruitflies, do. Studies of fruitflies show that they enter physiological states very much like mammal's sleep. They respond to medications such as caffeine and antihistamines much as we do. They sleep more when they have challenging days, and especially when they learn new things. Sleep deprivation makes them unable to learn effectively.

    The behaviour butterflies show is extremely similar to that described for sleeping fruitflies. They take longer to prepare for sleep than for short, light rest during the day. They have unique sleeping positions that they only use when entering this state. They are harder to rouse from this "sleep" stage then from simply resting, and are oblivious to fairly strong stimulus.

    All of this points to something I think we can call sleep. We don't yet know if they dream. I've included a couple of articles below.