Some authors of entomology textbooks describe it as a spiral dance. Other entomologists use the term circle dance. By either title, this butterfly behavior is something that many people witness during the summer months.
Here's how it works. Two butterflies - occasionally three - fly in an upward direction, trailing the leader. The flight pattern is in tight, ascending circles so that the butterflies appear to produce a spiral, thus the names ascribed to the activity.
This is not the only insect behavior that has been dubbed a dance by humans. Honey bees do what has been called the waggle dance. In this dance, a bee returning from a trip to the field will transmit information regarding the nectar or pollen source by doing a little dance. The name is based on the bee waggling her abdomen from side to side as part of the dance.
By definition, a dance is anything that has step sequences. Many dances have rhythm and are set to music. We also name our dances: the Charleston, hula, jitterbug, waltz, twist, cha-cha, and bunny hop are examples.
Why we humans dance is a matter for speculation, but we have been dancing for eons. Some suggest that dancing might be a way to communicate with others. Some people just dance for the fun of it. Such value in dancing was highlighted by Charles M. Schultz in his cartoon strip “Peanuts,” with Snoopy the dog doing his happy dance.
It has been suggested that dancing might be one way for humans to attract mates. It might be true. For sure, many other animals dance to attract mates. Some spiders do mating dances. Many birds do elaborate dance rituals as a way to attract mates. And that is what is going on with the butterfly spiral dance.
In the mating dance of the butterflies, females produce a pheromone, a scent to attract the male. Using sight and odor, the male follows the female in the spiral dance.
In his poem "The Butterfly," Robert Frost apparently recognized the reason for the butterfly dance and describes the flight:
"In airy dalliance,
Precipitate in love,
Tossed, tangled, whirled and whirled above,
Like a limp rose-wreath in a fairy dance."
Czech writers Karel and Josef Capek also understood the significance of the butterfly dance. In their 1921 play, "And So Ad Infinitum" (also known as "The Life of Insects"), the brothers Capek describe the dance in the prologue. They have a lepidopterist (an expert in butterflies and moths) who is collecting butterflies explain the behavior to a tramp: "The male pursues the female and the female allures, avoids - selects - the eternal round of sex!"
Many species of butterflies exhibit the spiral dance behavior, but here in the Midwest, the dance is most frequently observed in the white cabbage and yellow alfalfa butterflies. That is because these butterflies are the most common species across our landscapes.
Both the cabbage whites and the alfalfa butterflies are pest species. Their caterpillars feed on their namesake plants. The cabbage caterpillars are the worms found in cabbage, broccoli or Brussels sprouts. Alfalfa butterfly caterpillars feed on plants of the pea family.
We don't like to find caterpillars of these butterflies in our leafy, green vegetables. However, the presence of the butterflies fluttering about and feeding from flowers is still an enjoyable thing to see.
And watching those white butterflies spiraling upward is also neat to watch. That is, of course, until you stop to think that such a beautiful dance is just a precursor to finding worms in your cabbage!