SEPTEMBER
2003

 

 

 

By
Tom Turpin
 
Professor of
Entomology
Purdue University

 

 

 

 

 

09-11-03

A Very Good Year for Painted Lady Butterflies

To borrow a line from a song made famous by Frank Sinatra, "It was a very good year!" Such a line could apply to wine, to winning sports teams or even to the stock market. This year, it certainly applies to painted lady butterflies, at least in the Midwest.

Painted lady butterflies seem to be everywhere. They are so common on flowers that, when disturbed, the uprising resembles a dust storm. Roads are covered with resting painted ladies. So much so that a drive in the country often results in a car grill clogged with painted lady carcasses. 

The painted lady is about 2 inches from wing tip to wing tip. It is orange-colored with black patches and black wing tips. It also has four eye spots on the back side of the hind wing. Painted ladies are one of the most common butterfly species in the world. That is why they also are known as the cosmopolitan butterfly. Painted ladies are found in temperate regions around the world, except South America and Australia.

Even though the painted lady is widespread in temperate regions, it cannot survive cold winters. These butterflies die off each winter in North America, except in the Southwest. Each spring, these orange-and-black butterflies migrate northward. Before the growing season is over, they can be found everywhere except the most northern areas of Canada and Alaska.

How do the butterfly populations build up so quickly? First, they have a variety of food plants. The painted lady caterpillars can be found feeding on many species of wildflowers. They are especially common on thistle. In fact, painted ladies were once known as thistle butterflies. Their populations can also build up rapidly because they can go through several generations per year.

Because the populations can reach very high numbers in a short period of time, the caterpillars have been known to defoliate their food plants. One food plant is the soybean. When painted lady caterpillars are filling their guts on this crop plant, they would be considered pests. But to the delight of farmers, such an occasion is rare. Farmers would much rather see these insects feeding on thistles!

Painted lady butterflies also are reared in the classroom to demonstrate the metamorphosis of insects. In the classroom, the caterpillars feed on an artificial diet that resembles solid pea soup with some fiber in it. Once the caterpillar has completed feeding, it attaches itself to the lid of the container to form the pupa. In the wild, the pupa would be attached to the underside of a leaf or stem. Following emergence from the pupa, the butterflies mate and lay eggs. The complete life cycle takes less than three weeks.

The painted lady was given a scientific name by the famous founder of the system of binomial nomenclature -- the practice of giving a genus and species name to all living things. The name selected was Vanessa cardui. Vanessa is the Old English word for butterfly, probably based on the ancient goddess Venus. Cardui is based on Cardu, which is Latin for thistle, so the name means the butterfly of thistle!

 

Writer: Tom Turpin
Editor: Olivia Maddox